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about-claude/models/choosing-a-model Changed · +6 / -6 lines

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1111* **Capabilities:** What specific features or capabilities will you need the model to have to meet your needs?

1212* **Speed:** How quickly does the model need to respond in your application? [Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) delivers up to 2.5x higher output speed at premium pricing on [supported models](https://platform.claude.com/docs/en/build-with-claude/fast-mode#supported-models).

1313* **Cost:** What’s your budget for both development and production usage?

14* **Effort:** Several Claude models support an [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) that trades intelligence for latency and cost within a single model. Tuning effort is often a better lever than switching models. On Claude Fable 5.1, Claude Opus 5, and Claude Sonnet 5.5, start with the default (`high`) and adjust up or down based on your evals. On Claude Opus 5.5 and Claude Haiku 5.5 the default is `medium`; start there and adjust the same way. On Claude Opus 4.8 and Claude Opus 4.7, the `xhigh` effort level, between `high` and `max`, is the best setting for most coding and agentic use cases.

14* **Effort:** Several Claude models support an [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) that trades intelligence for latency and cost within a single model. Tuning effort is often a better lever than switching models. On Claude Fable 5.2, Claude Fable 5.1, Claude Opus 5, and Claude Sonnet 5.5, start with the default (`high`) and adjust up or down based on your evals. On Claude Opus 5.5 and Claude Haiku 5.5 the default is `medium`; start there and adjust the same way. On Claude Opus 4.8 and Claude Opus 4.7, the `xhigh` effort level, between `high` and `max`, is the best setting for most coding and agentic use cases.

1515

1616***

1717

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43432. [Optimize your prompts](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-opus-5-5) for this model.

44443. Evaluate if performance meets your requirements.

45454. Consider increasing efficiency by lowering [effort](https://platform.claude.com/docs/en/build-with-claude/effort) or downgrading models over time with greater workflow optimization.

465. If your evals at `xhigh` or `max` effort still fall short on demanding reasoning or long-horizon agentic work, move to [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1).

465. If your evals at `xhigh` or `max` effort still fall short on demanding reasoning or long-horizon agentic work, move to [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2).

4747

4848This approach is best for:

4949

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5555

5656**Claude Opus 5.5** (`claude-opus-5-5`) is built for long-running agentic coding and knowledge work, with [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) always on. If your integration forces tool use (`tool_choice` of type `any` or `tool`), turns thinking off, or uses the `computer_20251124` computer use tool, see [Breaking changes](https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5#breaking-changes) before switching.

5757

58**Claude Fable 5.1** (`claude-fable-5-1`) is Anthropic’s most capable model open to all customers. It extends Claude Fable 5 with stronger long-running agentic coding, knowledge work, and research at the same input and output prices, with cache reads at a quarter of the cost. **Claude Mythos 5.1** (`claude-mythos-5-1`) offers the same capabilities only to organizations verified through Anthropic’s verification programs, such as the [Cyber Verification Program](https://support.claude.com/en/articles/14604842). Both models use always-on [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking). See [What’s new in Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1) for details.

58**Claude Fable 5.2** (`claude-fable-5-2`) is Anthropic’s most capable model open to all customers. It’s built for demanding reasoning and long-horizon agentic work. **Claude Mythos 5.2** (`claude-mythos-5-2`) offers the same capabilities only to organizations verified through Anthropic’s verification programs, such as the [Cyber Verification Program](https://support.claude.com/en/articles/14604842). Both models use always-on [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking). If your code edits earlier turns of a conversation, moves a conversation between models, uses the `computer_20251124` computer use tool, or uses the advisor tool, see [Claude Fable 5.2 breaking changes](https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2#breaking-changes) before switching.

5959

6060For context windows, output limits, and prices, see the [model comparison table](https://platform.claude.com/docs/en/models/overview#latest-models-comparison).

6161

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6565

6666| When you need... | Consider starting with... | Example use cases |

6767| ------------------------------------------------------------------------- | ------------------------- | --------------------------------------------------------------------------------------------------------------------------------- |

68| The highest available capability | Claude Fable 5.1 | Agent sessions that run for hours, multistep deep research, analysis carried through to a finished document, spreadsheet, or deck |

68| The highest available capability | Claude Fable 5.2 | Agent sessions that run for hours, multistep deep research, analysis carried through to a finished document, spreadsheet, or deck |

6969| Complex agentic coding and enterprise work | Claude Opus 5.5 | Multihour autonomous coding agents, large-scale refactoring, complex systems engineering, vision-heavy workflows, computer use |

7070| Speed and capability for everyday coding, agent, and enterprise workloads | Claude Sonnet 5.5 | Code generation, data analysis, content creation, visual understanding, agentic tool use |

7171| The lowest latency and price | Claude Haiku 5.5 | Real-time applications, high-volume intelligent processing, cost-sensitive deployments needing strong reasoning, subagent tasks |

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9999 See detailed specifications and pricing for the latest Claude models

100100 </Card>

101101

102 <Card title="What’s new in Claude Fable 5.1" icon="sparkle" href="https://platform.claude.com/docs/en/models/fable-5-1/whats-new-fable-5-1">

103 Built for demanding reasoning and long-horizon agentic work

102 <Card title="What’s new in Claude Fable 5.2" icon="sparkle" href="https://platform.claude.com/docs/en/models/fable-5-2/whats-new-fable-5-2">

103 The latest Fable model: breaking changes, feature support, and pricing

104104 </Card>

105105

106106 <Card title="What’s new in Claude Opus 5.5" icon="sparkle" href="https://platform.claude.com/docs/en/models/opus-5-5/whats-new-opus-5-5">

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2323

2424Match your situation to a row.

2525

26| Your situation | Do this | Where |

27| ------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

28| Any workload, any model | Turn on prompt caching and trim unneeded tokens; both are free | [Cache repeated context](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#cache-repeated-context) · [Trim tokens](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#trim-input-and-context-tokens) |

29| A person waits between turns | Count the gaps between your requests, then pick the cache duration from the table in that section | [Pick the cache duration](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#pick-the-cache-duration) |

30| Costs are too high; quality is fine | Try lower effort on the model you use now | [Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort) |

31| You are not on the latest model | Upgrade; in Anthropic’s measurements each newer model solved at least as many tasks as the one before it, usually for less per solved task | [Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model) |

32| You are choosing or switching models | Compare on cost per completed task, not per token | [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) |

33| High-volume work with outputs you can check | Try Claude Haiku 5.5 first | [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) |

34| Quality isn’t good enough | If you lowered effort, restore it; otherwise try the next tier up at its default effort | [Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort) · [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) |

35| Attempts end with `stop_reason: max_tokens` | Raise `max_tokens` to 64,000: in Anthropic’s tests only 2 of about 14,000 turns were longer, and cost per solved task stayed about the same | [Set budgets](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#set-budgets-and-output-caps) |

36| You can check outputs (tests, a verifier) | Run at `low` effort and re-run failures at `high`: in Anthropic’s tests, about 40% lower cost than everything at `high`, at the same pass rate | [Re-run failures](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#re-run-failures-at-higher-effort) |

37| Agent loops with a few very costly runs | Set a Claude Managed Agents session budget and a workspace spend limit | [Set budgets](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#set-budgets-and-output-caps) |

38| You want agent runs to finish sooner | Tell the model time matters and show it the elapsed time: 7% to 47% less time in Anthropic’s tests, for a few points of score | [Show the model elapsed time](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#show-the-model-elapsed-time) |

39| A lower-cost model stalls only on hard decisions | Try an advisor. It can help only when your model consults it; first price its model alone at low effort and measure the consult rate | [Advisor strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#advisor-strategy-escalate-hard-decisions) |

40| The work exceeds one context window | Split the work and hand the parts to lower-cost models | [Orchestrator strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#orchestrator-strategy-delegate-bulk-work) |

26| Your situation | Do this | Where |

27| ------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

31| You are not on the latest model | Upgrade; on the coding benchmarks in that section each newer model solved at least as many tasks as the one before it, usually for less per solved task | [Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model) |

35| Attempts end with `stop_reason: max_tokens` | Raise `max_tokens` to 64,000: in Anthropic’s tests only 7 of about 18,000 turns were longer, and cost per solved task did not rise | [Set budgets](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#set-budgets-and-output-caps) |

4141

4242These results are Anthropic-internal ([Benchmarks referenced](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs)) and directional, not guarantees, so measure on your own workload with the [four-step method](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#measure-on-your-own-workload).

4343

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5252Turn on [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) before any other lever, because by default every turn of an agentic task resends the entire growing conversation: system prompt, tool definitions, and every prior turn.

5353

5454* A 40-turn task sends its first turn 40 times, so task cost grows with roughly the square of turn count.

55* Caching does not stop the resending, but each resend costs about a tenth as much (a twentieth on Claude Opus 5.5 and Claude Sonnet 5.5, a fortieth on Claude Fable 5.1 and Claude Mythos 5.1) and processes faster.

55* Caching does not stop the resending, but each resend costs about a tenth as much (a twentieth on Claude Opus 5.5 and Claude Sonnet 5.5, a fortieth on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1) and processes faster.

5656* The prefix is billed at the [cache-read rate](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#pricing) instead of the input price, and each turn pays the 1.25x cache-write rate only for what is new.

5757

5858[Message threads](https://platform.claude.com/docs/en/build-with-claude/message-threads), in beta, stop the resending while a thread lasts, until 5 minutes after its last request. They lower time to first token, not cost: the model still reads the whole conversation, so keep `cache_control` on every request. Threads don’t support compaction or most context editing.

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9090

9191#### Pick the cache duration

9292

93If your loop waits on a person between turns, use the [1-hour cache duration](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#1-hour-cache-duration) once about 1 turn in 20 follows a pause between 5 minutes and an hour and few gaps run over an hour. On Claude Fable 5.1, Claude Opus 5.5, and Claude Sonnet 5.5, keeping the 5-minute cache warm can cost less.

93If your loop waits on a person between turns, use the [1-hour cache duration](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#1-hour-cache-duration) once about 1 turn in 20 follows a pause between 5 minutes and an hour and few gaps run over an hour. On Claude Fable 5.2, Claude Fable 5.1, Claude Opus 5.5, and Claude Sonnet 5.5, keeping the 5-minute cache warm can cost less.

9494

9595The 1-hour duration costs more to write (2x the input price instead of 1.25x). A miss on either duration bills the whole prefix at the write price instead of the read price.

9696

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107107| Gaps over an hour are common: about 60% or more of your pauses longer than 5 minutes also run past an hour | Any | 5-minute default |

108108| Only 1 or 2 gaps in 20 fall between 5 minutes and an hour, and none lasts more than about half an hour | Claude Opus 5.5 and Claude Sonnet 5.5 | 5-minute cache kept warm, instead of the 1-hour duration |

109109| A pause comes before every turn | Claude Opus 5.5 and Claude Sonnet 5.5 | 1-hour duration |

110| Pauses run for minutes | Claude Fable 5.1 | 5-minute cache kept warm, instead of the 1-hour duration |

111| Pauses run toward an hour | Claude Fable 5.1 | 1-hour duration |

110| Pauses run for minutes | Claude Fable 5.1 and Claude Fable 5.2 | 5-minute cache kept warm, instead of the 1-hour duration |

111| Pauses run toward an hour | Claude Fable 5.1 and Claude Fable 5.2 | 1-hour duration |

112112

113113On Claude Haiku 5.5, use the “Any” rows: it reads the cache at the standard 0.1x the input price, twice the 0.05x of Claude Opus 5.5 and Claude Sonnet 5.5, so by list prices each keep-alive request costs twice as much, relative to the input price, as on those two models. A `max_tokens: 0` request refreshed its cache in a separate test (reference 16).

114114

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125125 * **Only 1 or 2 gaps in 20.** At default effort, keep-alive requests cost 8% to 13% less than the 1-hour duration on Claude Opus 5.5, 8% to 16% less on Claude Sonnet 5.5.

126126 * **A pause comes before every turn.** On Claude Opus 5.5 and Claude Sonnet 5.5, keep-alive requests cost a few percent more than the 1-hour duration at 6-minute pauses and over 50% more at 45-minute pauses.

127127

128* **Claude Fable 5.1**, whose [cache reads](https://platform.claude.com/docs/en/about-claude/pricing#prompt-caching) cost 0.025x the input price.

128* **Claude Fable 5.1 and Claude Fable 5.2**, whose [cache reads](https://platform.claude.com/docs/en/about-claude/pricing#prompt-caching) cost 0.025x the input price.

129129

130 * **Pauses run for minutes.** On Claude Fable 5.1, keep-alive requests[19](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) cost 13% to 20% less than the 1-hour cache, with 10% of turns paused and with a 6-minute pause before every turn.

131 * **Pauses run toward an hour.** On Claude Fable 5.1, only with a 45-minute pause before every turn did the 1-hour cache win, by about $0.12 USD on a session of 5 bug reports.

130 * **Pauses run for minutes.** On Claude Fable 5.2, keep-alive requests[19](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) cost about 4.5% to 19% less than the 1-hour cache, with 10% of turns paused and with a 6-minute pause before every turn.

131 * **Pauses run toward an hour.** On Claude Fable 5.2, only with a 45-minute pause before every turn did the 1-hour cache win, by about $0.12 USD[19](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) on a session of 5 bug reports.

132132

133133The following chart plots cost per session against the share of paused turns on Claude Sonnet 5.5:

134134

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145145**What to know.**

146146

147147* The 1-in-20 rule leaves a margin over the break-even of about 1 turn in 30. At 1 turn in 20 the 5-minute and the 1-hour setting cost about the same on Claude Sonnet 5.5, within run-to-run variation; at 1 turn in 10 the 5-minute setting cost 54% more (reference 16).

148* On models other than Claude Sonnet 5.5 and Claude Opus 5.5, prices put the break-even in the same range: every current model uses the same cache-write multipliers, and every model but Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, and Claude Sonnet 5.5 the same read price.

148* On models other than Claude Sonnet 5.5 and Claude Opus 5.5, prices put the break-even in the same range: every current model uses the same cache-write multipliers, and every model but Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, and Claude Sonnet 5.5 the same read price.

149149* The Claude Opus 5.5 and Claude Sonnet 5.5 keep-alive figures come from requests sent with `max_tokens: 1`. A `max_tokens: 0` request also refreshed an existing cache entry on Claude Fable 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 (reference 16).

150150

151151To keep the cache warm:

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158158

159159A `max_tokens: 0` request is rejected in the following cases:

160160

161* The request sets `thinking.type: "enabled"` (the default adaptive thinking on Claude Fable 5.1 is fine), structured outputs, or a forced tool choice ([its limitations](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#limitations)). On those workloads, buy the 1-hour duration instead.

161* The request sets `thinking.type: "enabled"` (the default adaptive thinking on Claude Fable 5.1 and Claude Fable 5.2 is fine), structured outputs, or a forced tool choice ([its limitations](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#limitations)). On those workloads, buy the 1-hour duration instead.

162162* The request carries the top-level `compaction` parameter, so don’t re-send a compaction request from [compaction on demand](https://platform.claude.com/docs/en/build-with-claude/compaction-on-demand) as a keep-alive request.

163163

164164<CodeGroup exclude="shell:CLI, python, typescript, csharp, go, java, php, ruby">

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198198 ![Bar chart: system prompt edit up to $1.26 USD, top-level effort change up to $1.02 USD, either in a message up to $0.026 USD](https://platform.claude.com/docs/images/cost-intel/cache-break-cost.svg)

199199</Frame>

200200

201At list prices, the stakes are highest on Claude Fable 5.1 and Claude Mythos 5.1, where a break rewrites the prefix at 1.25x the input price instead of reading it at 0.025x. On Claude Haiku 5.5, a system prompt edit cost 12.5x as much as an unchanged request, because the edit rewrote the whole conversation. On models that run the [prefix check](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#prefix-check), a request that makes this edit and sends earlier thinking blocks back can get a 400 error instead[18](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). The top-level effort change, in a conversation that held the model’s first reply with its thinking, rewrote all but the system prompt. These figures are from the Messages API.

201At list prices, the stakes are highest on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1, where a break rewrites the prefix at 1.25x the input price instead of reading it at 0.025x. On Claude Haiku 5.5, a system prompt edit cost 12.5x as much as an unchanged request, because the edit rewrote the whole conversation. On models that run the [prefix check](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#prefix-check), a request that makes this edit and sends earlier thinking blocks back can get a 400 error instead[18](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). On Claude Fable 5.2 and Claude Mythos 5.2, every account gets the 400 error by default, including accounts created before August 31, 2026. The top-level effort change, in a conversation that held the model’s first reply with its thinking, rewrote all but the system prompt. These figures are from the Messages API.

202202

203203**What to do.**

204204

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274274* Run-wide, the prune and context editing cache about equally well. If you use context editing, [clear in a few large batches](https://platform.claude.com/docs/en/build-with-claude/context-editing#context-editing-and-prompt-caching).

275275

276276<Note>

277 On Claude 5.1 and later models, rewriting an earlier tool result [invalidates every thinking block after it](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#prefix-check), so use compaction instead. The prune was measured on an earlier model without [preserved thinking](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking); on these models, [context editing](https://platform.claude.com/docs/en/build-with-claude/context-editing) and [compaction](https://platform.claude.com/docs/en/build-with-claude/compaction) run on the server and don’t invalidate thinking blocks. [Send assistant turns back exactly as returned](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#append-assistant-turns-exactly-as-returned): dropping their thinking blocks costs output tokens on every turn, because Claude [re-creates the reasoning](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#drop-block-cost).

277 On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5, rewriting an earlier tool result [invalidates every thinking block after it](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#prefix-check), so use compaction instead. The prune was measured on an earlier model without [preserved thinking](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking); on these models, [context editing](https://platform.claude.com/docs/en/build-with-claude/context-editing) and [compaction](https://platform.claude.com/docs/en/build-with-claude/compaction) run on the server and don’t invalidate thinking blocks. [Send assistant turns back exactly as returned](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#append-assistant-turns-exactly-as-returned): dropping their thinking blocks costs output tokens on every turn, because Claude [re-creates the reasoning](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#drop-block-cost).

278278</Note>

279279

280280The prune, adapted from the triage agent’s code:

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384384

385385## Trade cost against intelligence

386386

387These levers set where a single model sits between cost and intelligence: model choice, effort, re-running failures at a higher setting, the budgets and caps it works within, and whether it can see how much time has passed. If you are a model or two behind, upgrade first ([Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model)); otherwise, start with an effort sweep on your current model ([Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort)). From lowest to highest cost and capability, the current models are Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, and Claude Fable 5.1 (the frontier model); [Models overview](https://platform.claude.com/docs/en/models/overview) has the full lineup and prices.

387These levers set where a single model sits between cost and intelligence: model choice, effort, re-running failures at a higher setting, the budgets and caps it works within, and whether it can see how much time has passed. If you are a model or two behind, upgrade first ([Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model)); otherwise, start with an effort sweep on your current model ([Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort)). From lowest to highest cost and capability, the current models are Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, and Claude Fable 5.2 (the frontier model); [Models overview](https://platform.claude.com/docs/en/models/overview) has the full lineup and prices.

388388

389389### Compare models on cost per task

390390

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409409| GPQA Diamond[9](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) | Claude Haiku 5.5 | `medium` (default) | 85% accuracy, compared with 91% for each of Claude Opus 5.5 and Claude Sonnet 5.5 | About a twentieth of Claude Opus 5.5’s cost per correct answer and about a tenth of Claude Sonnet 5.5’s |

411411

412On 463 of the 478 problems in the SWE-bench Pro subset, the ones whose reference solutions also pass with no network access (reference 3), Claude Fable 5.2 at `high`, its default on the Messages API, solved 96.3% of tasks for $1.39 USD per solved task. The same Claude Fable 5.1 run at its default, counted over these 463 problems, solved 92.4% for $1.17 USD. At `low`, Fable 5.2 solved 94.6% for $0.39 USD per solved task: more tasks than Fable 5.1 at its default, for about a third of the cost. At a similar pass rate, Claude Opus 5.5 still costs less per solved task on these problems: at its default it solved 93.1% for $0.22 USD, at `high` 95.5% for $0.30 USD, and at `xhigh` 96.5% for $0.75 USD, level with Fable 5.2 at `high` for a little over half the cost.

413

412414**What to do.**

413415

414* Start with Claude Opus 5.5 at its default effort: on the SWE-bench Pro subset it matched Claude Fable 5.1 at its default, inside run-to-run noise, for about a fifth of the cost per solved task. Opus 5.5 and Fable 5.1 both largely saturate the SWE-bench Pro subset. Use Claude Fable 5.1 for demanding reasoning and long-horizon agentic work, or when your evals on Claude Opus 5.5 at higher effort still fall short.

416* Start with Claude Opus 5.5 at its default effort: on the SWE-bench Pro subset it matched Claude Fable 5.1 at its default, inside run-to-run noise, for about a fifth of the cost per solved task. Opus 5.5 and Fable 5.1 both largely saturate the SWE-bench Pro subset. Use Claude Fable 5.2 for demanding reasoning and long-horizon agentic work, or when your evals on Claude Opus 5.5 at higher effort still fall short.

415417* At the other end, Claude Haiku 5.5 suits high-volume and latency-sensitive work with checkable outputs.

416418* Price every candidate in cost per completed task on your own traffic, including Claude Opus 5.5 at its default effort and the frontier model at reduced effort. Each of Claude Opus 5.5’s token prices, cache reads included, is twice Claude Sonnet 5.5’s, but on the SWE-bench Pro subset Opus 5.5 at `low` solved about the same share of tasks as Sonnet 5.5 at its default, inside run-to-run noise, for about 7% more per solved task.

417* Measure what a more expensive model buys on your own workload. On the 45 DeepResearch Bench II[7](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) tasks scored for every model, at default effort, Claude Opus 5.5 scored 2.6 points above Claude Sonnet 5.5 for 1.5 times the cost per task, and Claude Fable 5.1 scored 6.0 points above Claude Sonnet 5.5 for 5.8 times. On all 50 tasks, with four biology tasks that only Claude Sonnet 5.5 answered counted as failures, neither is measurably ahead of Claude Sonnet 5.5.

419* Measure what a more expensive model buys on your own workload. On the 44 DeepResearch Bench II[7](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) tasks scored for every model, at default effort on the Messages API, Claude Opus 5.5 scored 2.4 points above Claude Sonnet 5.5 for 1.5 times the cost per task. Claude Fable 5.2 cost 4.3 times as much as Claude Sonnet 5.5 for no measurable gain in score, and 2.9 times as much as Claude Opus 5.5 for a score 1.9 points lower. Against Claude Fable 5.1, it cost 20% to 61% less at each effort level and scored 4.7 to 7.0 points lower. On all 50 tasks, Claude Opus 5.5 is not measurably ahead of Claude Sonnet 5.5: safeguards nearly always stopped it on four biology tasks that Claude Sonnet 5.5 answered, and a stopped attempt counts as a failure.

418420* Price the tail of your workload, not the median: compare models on the hardest tenth of your tasks, not the typical one.

419421

420422The bill is decided by the tasks the cheaper model fails, because a failed task still bills its tokens, then the retry, then whatever the failure costs downstream. The tail is also where the money goes even when nothing fails. On a 20-problem WideSearch[1](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) run, two problems carried 43% of the spend:

from line 429

427429

428430### Upgrade the model

429431

430If you are a model or two behind, the cheapest lever is the model string. In Anthropic’s measurements, each newer model solved at least as many tasks as the one before it, usually for less per solved task. The chart plots recent Claude models on two benchmarks in which an agent works alone on one written task and tests check the result: the SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset, where every model ran through the same test setup, and Terminal-Bench 3[20](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). The table lists what each upgrade changed:

432If you are a model or two behind, the cheapest lever is the model string. On the coding benchmarks in this section and in [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task), each newer model solved at least as many tasks as the one before it; most cost less per solved task, and Claude Fable 5.2, at `high`, cost more than Claude Fable 5.1. On a research benchmark, Claude Fable 5.2 did the reverse: it cost less per task than Claude Fable 5.1 at each effort level and scored lower ([Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task)). The chart plots recent Claude models on two benchmarks in which an agent works alone on one written task and tests check the result: the SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset, where every model ran through the same test setup, and Terminal-Bench 3[20](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). The table lists what each upgrade changed:

431433

432434<Frame>

433435 ![Charts: on SWE-bench Pro, Opus 5.5 and Sonnet 5.5 cut cost per solved task most; on Terminal-Bench 3, Opus drops to $28 USD](https://platform.claude.com/docs/images/cost-intel/upgrade-ladder-sonnet-5-5.svg)

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452454

453455### Tune effort

454456

455Sweep effort on your own workload before you add a second model. Lower effort costs less and is often faster, and how much accuracy it gives up depends on the task: on long-horizon coding, effort bought accuracy, and on research tasks it bought a lot in one measurement and a little in another. The [`effort`](https://platform.claude.com/docs/en/build-with-claude/effort) parameter governs how much thinking, tool calling, and self-verification the model does; `high` is the default on most models, and `medium` on Claude Opus 5.5 and Claude Haiku 5.5.

457Sweep effort on your own workload before you add a second model. Lower effort costs less and is often faster, and how much accuracy it gives up depends on the task: on long-horizon coding, effort bought accuracy, and on research tasks it bought a lot in one measurement and a little in another. The [`effort`](https://platform.claude.com/docs/en/build-with-claude/effort) parameter governs how much thinking, tool calling, and self-verification the model does; on the Messages API, `high` is the default on most models, and `medium` on Claude Opus 5.5 and Claude Haiku 5.5.

456458

457459The following table lists Anthropic’s measurements on two benchmarks with current models; scores and costs are not comparable between the two benchmarks. Costs are per task, not per solved task as in [Compare models on cost per task](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task). Each score pools two runs on SWE-bench Pro and three on DeepResearch Bench II, unless its cell says otherwise:

458460

460| -------------------------------------------------------------------------------------------------------------------------------------- | ---------------- | ------------------ | ------------------------------------ | ------------- |

461| SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset | Claude Opus 5.5 | `low` | 87.4% of tasks solved | $0.11 USD |

465| DeepResearch Bench II[7](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) | Claude Fable 5.1 | `low` | Rubric score 60.5% | $3.47 USD |

462| -------------------------------------------------------------------------------------------------------------------------------------- | ---------------- | ------------------------------------ | ------------------------------------ | ------------- |

463| SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset | Claude Opus 5.5 | `low` | 87.4% of tasks solved | $0.11 USD |

467| DeepResearch Bench II[7](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) | Claude Fable 5.2 | `low` | Rubric score 54.5% | $1.49 USD |

468470

469471The following chart plots accuracy against cost per task for Claude Opus 5.5 on the SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset:

470472

from line 485

483485* Sweep two or three effort levels on a sample of your own traffic, each in a separate session: changing top-level effort mid-session [invalidates the cache](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#cache-repeated-context) and distorts the comparison. The curve is the baseline any multi-model strategy must beat ([step 2 of measuring on your own workload](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#measure-on-your-own-workload)).

484486* On long-horizon coding, effort is a real tradeoff, which [re-running failures at higher effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#re-run-failures-at-higher-effort) turns back into a saving. At `medium`, Claude Sonnet 5.5 scored about 7 points lower than at its default, `high`, on the SWE-bench Pro[3](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) subset for about 59% of the cost per task (2 runs each), and scored 62.7% compared with 77.8% on the internal agentic-coding benchmark[11](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) (1 attempt per task).

485487* At `xhigh` and `max`, Claude Sonnet 5.5 can start its own rounds of review after it finishes a task, which takes more time and tokens. To keep that work on the task, add the prompt under “Thoroughness at `xhigh` and `max` effort” in [Prompting Claude Sonnet 5.5](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-sonnet-5-5#steer-initiative-and-scope) to your system prompt.

486* On research tasks, measure the model you ship. Claude Fable 5.1 scored 2.5 points higher at `high` than at `low` on DeepResearch Bench II, for 1.6 times the cost, and no higher at `medium` than at `low`; Claude Opus 5.5 scored 13.3 points lower at `low` than at `medium` on DRACO[21](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). The two results come from different models on different benchmarks, so they show that the answer varies, not why.

488* On research tasks, measure the model you ship. Claude Fable 5.2 scored 3.3 points higher at `high` than at `low` on DeepResearch Bench II, for 3.2 times the cost, and not measurably higher at `medium` than at `low`; Claude Opus 5.5 scored 13.3 points lower at `low` than at `medium` on DRACO[21](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs). The two results come from different models on different benchmarks, so they show that the answer varies, not why.

487489* At `low`, Claude Opus 5.5’s typical task took 84% less time than at `medium` on DRACO[21](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), 30% less on HLE[22](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), and 47% less on an internal set of physics problems[23](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), and it scored 13.3, 3.4, and 14.0 points lower (3, 3, and 4 attempts per task).

488* On an internal defect-search benchmark[8](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) (10 runs per setting), Claude Opus 5.5 scored 34 points lower at `low` than at `medium`, for about a fifth of the cost. Claude Fable 5.1 scored 1.8 points lower at `low` than at `high`, for about a quarter less.

490* On an internal defect-search benchmark[8](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs) (10 runs per setting), Claude Opus 5.5 scored 34 points lower at `low` than at `medium`, for about a fifth of the cost. Claude Fable 5.2 scored 4.3 points lower at `low` than at `high`, for 37% less.

489491

490492### Re-run failures at higher effort

491493

from line 522

520522* Set `max_tokens` to 64,000 for agentic work, or to 128,000, the maximum, when a single cut-off attempt is costly. [Stream responses](https://platform.claude.com/docs/en/build-with-claude/streaming) that large, treat [`stop_reason: max_tokens`](https://platform.claude.com/docs/en/build-with-claude/handling-stop-reasons#max-tokens) as a failure, and save money with effort, which the model can see.

521523* On Claude Haiku 5.5, raise a small `max_tokens` or lower effort: thinking is on by default and counts toward the cap, so a response can end before any text (see the [Claude Haiku 5.5 migration guide](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#configure-thinking)).

522524

523The following table shows what each model solved and what a solved task cost at each cap on an internal repository-task benchmark[12](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), one attempt per task, each model at its default effort. The rows at 16,384 average two runs, and the other rows are one run each:

525The following table shows what each model solved and what a solved task cost at each cap on an internal repository-task benchmark[12](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), one attempt per task, each model at its default effort on the Messages API. The rows at 16,384 average two runs, and the other rows are one run each:

524526

526| ---------------- | ------------ | ------------------------- | ------------ | ------------------------ |

527| Claude Opus 5.5 | 16,384 | 25% | 57.6% | $5.38 USD at list prices |

528| Claude Opus 5.5 | 64,000 | 0% | 75.6% | $5.38 USD at list prices |

529| Claude Opus 5.5 | 128,000 | 0% | 68.9% | $5.94 USD at list prices |

530| Claude Fable 5.1 | 16,384 | 43% | 36.3% | $21.37 USD as billed |

531| Claude Fable 5.1 | 64,000 | 0% | 58.5% | $21.53 USD as billed |

532| Claude Fable 5.1 | 128,000 | 1% | 60.0% | $21.74 USD as billed |

528| ---------------- | ------------ | ------------------------- | ------------ | ------------------------- |

529| Claude Opus 5.5 | 16,384 | 25% | 57.6% | $5.38 USD at list prices |

530| Claude Opus 5.5 | 64,000 | 0% | 75.6% | $5.38 USD at list prices |

531| Claude Opus 5.5 | 128,000 | 0% | 68.9% | $5.94 USD at list prices |

532| Claude Fable 5.2 | 16,384 | 85% | 20.3% | $27.96 USD at list prices |

533| Claude Fable 5.2 | 64,000 | 2% | 77.4% | $24.42 USD at list prices |

534| Claude Fable 5.2 | 128,000 | 0% | 78.2% | $24.52 USD at list prices |

533535

534536**Claude Opus 5.5 at 64,000 and 128,000:** No attempt was cut off at either cap, so the cap does not explain why these two rows differ in tasks solved or in cost per solved task. Each row is one run.

535537

536Compare the caps within each model. The two models were run a month apart, and their costs are priced on different bases.

538Compare the caps within each model. The two models were measured in separate runs.

537539

538On the internal repository tasks[12](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), almost every turn finishes far below a 16,384-token cap. The rare long turn is what a higher cap buys:

540On the internal repository tasks[12](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), almost every turn finishes far below a 16,384-token cap, but one longer turn ends the whole attempt: with a higher cap, 1.7% of Claude Fable 5.2’s turns passed 16,384 tokens, and at 16,384 the cap ended 85% of its attempts. The rare long turn is what a higher cap buys (Claude Opus 5.5 and Claude Fable 5.1 are the two models in this chart):

539541

540542<Frame>

541543 ![Dot plot of per-turn output for Opus 5.5 and Fable 5.1: medians a few hundred tokens, longest 61k and 128k, against the caps](https://platform.claude.com/docs/images/cost-intel/max-tokens-ladder-opus-5-5.svg)

542544</Frame>

543545

544Ask for shorter answers. Output tokens cost five times input tokens on Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, and Claude Fable 5.1, and in an agent loop every token the model writes comes back as input on every later turn, so you pay for a long answer again and again.

546Ask for shorter answers. Output tokens cost five times input tokens on Claude Haiku 5.5, Claude Sonnet 5.5, Claude Opus 5.5, Claude Fable 5.2, and Claude Fable 5.1, and in an agent loop every token the model writes comes back as input on every later turn, so you pay for a long answer again and again.

545547

546548In a measurement on an earlier model[26](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), Anthropic ran a small agent that triages bug reports ([Trim input and context tokens](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#trim-input-and-context-tokens)) under three final-answer instructions, three runs each, with the same model and tools:

547549

from line 573

571573 ![Scatter and bar charts, DRACO, HLE, and the physics set: the changes save the most time on DRACO, for a few points of score](https://platform.claude.com/docs/images/cost-intel/time-awareness.svg)

572574</Frame>

573575

574To pay for speed instead, set `speed: "fast"` on Claude Opus 5.5. [Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) gives up to 2.5x higher output tokens per second at twice the standard token prices. Switching speed mid-conversation misses the prompt cache.

576To pay for speed instead, set `speed: "fast"` on Claude Fable 5.2 or Claude Opus 5.5. [Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) gives up to 2.5x higher output tokens per second at twice the standard token prices. Switching speed mid-conversation misses the prompt cache.

575577

576578## Combine models

577579

from line 640

638640 ![Diagram of the orchestrator strategy: a frontier model fans subtasks out to three lower-cost worker models](https://platform.claude.com/docs/images/model-routing-orchestrator-strategy.svg)

639641</Frame>

640642

641The following chart plots 9 of the defect-search benchmark’s 12 configurations by cost and score:

643The following chart plots 9 of the defect-search benchmark’s 17 configurations by cost and score (none of Claude Fable 5.2’s five):

642644

643645<Frame>

644646 ![Scatter chart, defect search: Opus 5.5 with Sonnet 5.5 subagents matches Opus 5.5 alone, at medium, for about a third less](https://platform.claude.com/docs/images/cost-intel/corpus-pareto.svg)

from line 649

647649**What to do.**

648650

649651* **Routine work with a long cost tail:** measure this case first, for accuracy as well as cost. The measurement behind it covers only problems that the delegated configuration answered correctly in every run (reference 4).

650* **Work larger than one context window:** split it into parts, one session or one subagent per part. On the defect-search benchmark[8](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), Claude Opus 5.5 with Claude Sonnet 5.5 subagents cost about a third less than one Claude Opus 5.5 session per part at its default effort, and scored about the same. Claude Fable 5.1 as the orchestrator in Claude Opus 5.5’s place cost 24% more for no measurable gain. Alone, Claude Fable 5.1 cost 2.2 to 3.0 times as much as Claude Opus 5.5 at `high` and scored no higher.

652* **Work larger than one context window:** split it into parts, one session or one subagent per part. On the defect-search benchmark[8](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs), Claude Opus 5.5 with Claude Sonnet 5.5 subagents cost about a third less than one Claude Opus 5.5 session per part at its default effort, and scored about the same. Claude Fable 5.2 as the orchestrator in Claude Opus 5.5’s place cost 19% more and scored about the same. Alone, from `low` to `high`, Claude Fable 5.2 scored 1.6 to 5.9 points higher than Claude Opus 5.5 alone at `high`, for 1.5 to 2.4 times the cost, and 3.2 to 7.5 points higher than with Claude Sonnet 5.5 subagents, for 2.2 to 3.4 times the cost. It also scored higher than Claude Fable 5.1 alone at each effort level: 3.6 points at `low`, for 32% less; 3.8 at `medium`, for 37% less; and 6.1 at `high`, for 21% less.

651653* **Claude Haiku 5.5 subagents on coding tasks:** compare them with lower effort first. On an internal coding benchmark on Claude Managed Agents, they were an alternative to lowering effort, not better. Adding them to Claude Opus 5.5 at `medium`, with a short delegation prompt, cut cost per attempt by 32% and the pass rate by about 4 percentage points (95% interval 1.3 to 7.1), about what a mix of `low` and `medium` without subagents would give at that cost[29](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#refs).

652654

653655## Measure on your own workload

from line 866

864866| Data files through code execution | 92% on a data task of 25 questions, with prompt caching off | A gain: 25 of 25 correct instead of 7 | Faster | [Trim input and context tokens](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#trim-input-and-context-tokens) |

866868| Prompt audit against the current model | 14% on both model upgrades tested | None; a gain on one | Faster (fewer tool rounds) | [Audit prompts against the current model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#audit-prompts-against-the-current-model) |

867| Upgrade the model | Usually less: up to 40% less on typical workloads, and up to 87% less per solved task on a coding benchmark | None; a gain on most | Neutral | [Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model) |

868| Lower effort | On long coding tasks, `medium` cost about 30% to 52% less than `high`, and `low` about two thirds less | Up to 34 points lower, depending on the task and the model; 2.5 on one research agent | Faster | [Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort) |

869| Upgrade the model | Usually less: up to 40% less on typical workloads, and up to 87% less per solved task on a coding benchmark | None on coding, a gain on most; lower on one research benchmark for Claude Fable 5.2 | Neutral | [Upgrade the model](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#upgrade-the-model) |

870| Lower effort | On long coding tasks, `medium` cost about 30% to 52% less than `high`, and `low` about two thirds less | Up to 34 points lower, depending on the task and the model; 3.3 on one research agent | Faster | [Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort) |

869871| Re-run failures | About 40% less than running everything at `high`, at the same pass rate or slightly better | None | A second attempt on the tasks that fail | [Re-run failures at higher effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#re-run-failures-at-higher-effort) |

871| Raising `max_tokens` | None: cost per solved task stayed about the same | A gain: up to 22 points more tasks solved on one coding benchmark; none on another | Neutral | [Set budgets and output caps](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#set-budgets-and-output-caps) |

873| Raising `max_tokens` | None: cost per solved task did not rise at 64,000 | A gain: up to 57 points more tasks solved at 64,000 on one coding benchmark; none on another | Neutral | [Set budgets and output caps](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#set-budgets-and-output-caps) |

872874| Advisor | None: about 2.1 times the cost of the model alone, on a coding benchmark | On coding, a small gain that may be chance; on chart reading, a loss | About 1.4 extra calls per attempt, on coding | [Advisor strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#advisor-strategy-escalate-hard-decisions) |

873875| Orchestrator | With subagents on the next model down, about a third less than the orchestrator’s model alone at its default effort, on work larger than one context window; on routine work, measure first | No measurable loss on that work | Up to 25 subagents at a time | [Orchestrator strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#orchestrator-strategy-delegate-bulk-work) |

874876| Fast mode | None: twice the standard token prices | None | Up to 2.5x higher output tokens per second | [Show the model elapsed time](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#show-the-model-elapsed-time) |

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925927 * **Advisor, Claude Sonnet 5 pairings:** The Claude Sonnet 5 executor pairings with a Claude Opus 5 advisor behind the consult-rate examples in [Advisor strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#advisor-strategy-escalate-hard-decisions) ran on this subset through the same test setup: the pairing at the default effort was run twice (August 7 and August 8, 2026, a run and an exact replication), the low-effort pairing once (August 8, 2026), and, ten days later, Claude Sonnet 5 alone twice at its default effort (77.4%, the baseline for both pairings).

926928 * **Advisor, Claude Sonnet 5.5 consult check:** The Claude Sonnet 5.5 consult check cited in [Advisor strategy](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#advisor-strategy-escalate-hard-decisions) ran one attempt on each of 20 of the 478 problems, on September 24, 2026, with a Claude Opus 5.5 advisor through the advisor tool. Four configurations ran: `high` and `xhigh`, each with and without the advisor tool documentation’s suggested system prompt for coding tasks. At its default effort, `high`, Claude Sonnet 5.5 did not consult the advisor on any of the 20 problems, with or without the prompt. At `xhigh`, it consulted on 3 of the 20 problems without the prompt and 4 with it, each time on its attempts with the most turns.

927929 * **Escalation figures:** Escalation figures come task by task from the Opus 5.5 runs: `low` first, then `high` on its failures, solved 96.4% to 97.5% across run pairings for about $0.17 USD; `medium` first, 96.0% to 97.1% for about $0.24 USD; `high` re-run on its own failures, 96.9% for $0.31 USD; everything at `high`, 94.8% to 95.8% for $0.29 USD.

928 * **Compare models:** The Claude Fable 5.1 figure in [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) comes from one run on the same subset at the default effort, run August 26, 2026: counted over the 478 problems, it solved 92.3% for $1.19 USD per solved task. That section’s chart and its Claude Opus 5.5 and Claude Sonnet 5.5 figures pool the two runs at each setting plotted, all counted over the 478 problems: Claude Opus 5.5 at `low`, `medium`, and `high`, and Claude Sonnet 5.5 at `medium` and `high`.

930 * **Compare models:** The Claude Fable 5.1 figure in [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) comes from one run on the same subset at the default effort, run August 26, 2026: counted over the 478 problems, it solved 92.3% for $1.19 USD per solved task. That section’s chart and its table’s Claude Opus 5.5 and Claude Sonnet 5.5 figures pool the two runs at each setting plotted, all counted over the 478 problems: Claude Opus 5.5 at `low`, `medium`, and `high`, and Claude Sonnet 5.5 at `medium` and `high`. Claude Fable 5.2 figures are one run each at `low` and at `high` (its default on the Messages API), both with the same 16,384-token cap per turn, which cut off 8 of the 463 `high` attempts and none at `low`; cut-off attempts count as failures. One more `high` attempt was stopped by a safety monitor in the evaluation environment before it finished and also counts as a failure, although the changes it had made by then passed the tests; leaving it out would give 96.5% for `high`. Those runs used a version of the benchmark whose grading containers have no network access. Of the 478 problems used for the Opus 5.5 comparisons, the reference solution fails without network access on 15, so the Fable 5.2 comparisons use the remaining 463. In those comparisons, the Claude Opus 5.5 figures are the same runs counted over the 463 problems: two runs each at `medium` and `high`, and one at `xhigh`. The Claude Fable 5.1 and Claude Opus 5.5 figures set beside them were graded with network access, so only the problem set is matched, not the grading setup. Claude Fable 5.2’s costs use the metering described under How priced, applied to each attempt’s token totals rather than to each request separately, so they are estimates.

929931 * **Compare models, work per task:** In those figures, Claude Opus 5.5 at `low` did less work on each task than Claude Sonnet 5.5 at its default: a little over half of Sonnet 5.5’s output tokens and a little over a third of its cache reads. At their defaults, Opus 5.5 at `medium` solved about 5 percentage points more than Sonnet 5.5 for about twice the cost. At that setting it did slightly more work per task than Sonnet 5.5.

930932 * **Upgrade the model, runs:** The Claude Fable 5 point in Upgrade the model pools three runs at the default effort, run August 26, 2026, priced as a customer’s organization is metered. The upgrade ladder counts every model over the 478 problems, each at its shipped defaults. It uses one run per model except Opus 5, Opus 5.5, Sonnet 5, and Sonnet 5.5 (two runs each) and Fable 5 (the three runs described above). The Opus 4.7, Opus 4.8, Sonnet 4.6, and Sonnet 5 runs ran August 17 to 19, 2026, and the Opus 5 runs on August 4, all in one harness and organization; the Opus 5.5 and Sonnet 5.5 runs are the ones described earlier in this reference.

931933 * **Upgrade the model, cost per solved task:** Claude Opus 5 costs 21% more per solved task than Claude Opus 4.8 when those Claude Opus 5 runs are compared with one Claude Opus 4.8 run at its shipped defaults from the August 17 to 19 series, counted over the same 478 problems; the chart’s SWE-bench Pro panel shows neither Claude Opus 4.7 nor Claude Opus 4.8. In the same measurements, priced as a customer is billed, Claude Opus 5 solves 12 more points of tasks than Claude Opus 4.8 at that 21% more per solved task, Claude Opus 4.8 solves the same share of tasks as Claude Opus 4.7 for 14% less per solved task, and Claude Opus 5 at `low` effort beats Claude Opus 4.8’s default on this benchmark for about 30% of its cost per solved task.

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941943

9429447. **DeepResearch Bench II:** Li et al., “DeepResearch Bench II: Diagnosing Deep Research Agents via Rubrics from Expert Report,” arXiv:2601.08536, 2026.

943945

944 * **What was measured:** Its 132 research tasks across 22 domains are graded against expert-derived binary rubrics. Measured October 22, 2026, on a 50-task subset drawn from all its themes, half in English and half in Chinese, one attempt per task, 3 runs per setting: Claude Sonnet 5.5 at `high`, Claude Opus 5.5 at `medium`, and Claude Fable 5.1 at `low`, `medium`, and `high`. Every setting ran on the Messages API with adaptive thinking and the production safety classifiers on.

945 * **Tools:** The agent used search and fetch tools that the evaluation harness hosts over an Anthropic web index with nothing dated after March 17, 2026, and had no shell. A search query over 120 characters was cut at the last whole word, and the agent was told so: 48% of searches on Claude Sonnet 5.5, and 26% to 31% in the other settings. About a quarter of fetches returned an error. Each task’s source article and the benchmark’s own paper and dataset were filtered out.

946 * **How scored:** Claude Opus 4.6 judges under the benchmark’s rubric protocol; the original uses a different judge, and an Anthropic judge may favor the house style. Scores are means over the 45 tasks that every setting answered and the judge fully graded. The other five: four biology tasks that the safety classifiers refused in every run of Claude Opus 5.5 and Claude Fable 5.1 and in none of Claude Sonnet 5.5’s, and one on which a safety check that Anthropic adds to its own evaluations stopped an attempt.

947 * **Scores:** On the 45 tasks, and on all 50, with a refused or stopped attempt counted as 0: Claude Sonnet 5.5, 56.9% and 57.0%; Claude Opus 5.5, 59.5% and 54.3%; Claude Fable 5.1, 60.5% and 55.1% at `low`, 60.5% and 54.9% at `medium`, and 63.0% and 57.4% at `high`. Task-by-task differences on the 45 tasks, taken before rounding, with 95% intervals: Claude Fable 5.1 at `high` over `low`, 2.5 points (1.3 to 3.6); Claude Opus 5.5 over Claude Sonnet 5.5, 2.6 (0.7 to 4.5); Claude Fable 5.1 at `high` over Claude Opus 5.5, 3.4 (2.0 to 4.9), and over Claude Sonnet 5.5, 6.0 (4.4 to 7.7); Claude Fable 5.1 at `medium` over `low`, 0.0 (-1.3 to 1.2). On all 50 tasks: Claude Opus 5.5 over Claude Sonnet 5.5, -2.7 (-8.3 to 2.9); Claude Fable 5.1 at `high` over Claude Sonnet 5.5, 0.4 (-5.3 to 6.2).

948 * **How priced:** Each cost per task is the model’s own tokens at list prices, from the attempts’ usage records, over all 50 tasks and every attempt, averaged over the three runs: $1.05 USD on Claude Sonnet 5.5, $1.52 USD on Claude Opus 5.5, and $3.47 USD, $4.44 USD, and $5.64 USD on Claude Fable 5.1. A refused attempt costs about a cent. On the 45 tasks alone the costs are $1.06 USD, $1.63 USD, $3.75 USD, $4.81 USD, and $6.10 USD. The cost ratios in [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task), 1.5 and 5.8, are on those 45 tasks, like the scores beside them; over all 50 tasks they are 1.4 and 5.4. Costs cover model tokens only; the harness’s tools add no charges. The agent made 17 to 28 searches per task, refused attempts counted.

949 * **Caching chart:** The caching chart re-prices the same requests with every input token at the uncached rate. The evaluation harness set the cache breakpoints.

946 * **What was measured:** Its 132 research tasks across 22 domains are graded against expert-derived binary rubrics. Measured November 3, 2026, on a 50-task subset drawn from all its themes, half in English and half in Chinese, one attempt per task, 3 runs per setting: Claude Sonnet 5.5 at `high`, Claude Opus 5.5 at `medium`, and Claude Fable 5.1 and Claude Fable 5.2 at `low`, `medium`, and `high`. Every setting ran on the Messages API with adaptive thinking, and the three released models with the production safety classifiers on. Claude Fable 5.2 was run before its release, on 46 of the 50 tasks, without the four biology tasks.

947 * **Tools:** The agent used search and fetch tools that the evaluation harness hosts over an Anthropic web index with nothing dated after March 17, 2026, and had no shell. A search query over 120 characters was cut at the last whole word, and the agent was told so: 57% to 59% of searches on Claude Fable 5.2, 49% on Claude Sonnet 5.5, and 26% to 31% in the other settings. Within a task, Claude Fable 5.2’s runs with more cut searches did not score lower. Further runs of Claude Fable 5.2 and Claude Opus 5.5 followed on November 6 and 7, 2026, three per model in each of two sets. The tool cut longer queries as before in one set and refused them in the other. On the 43 tasks scored in both sets, Claude Fable 5.2 at `high` scored 0.9 points below Claude Opus 5.5 with the cut (95% interval 1.0 above to 2.7 below). That interval includes the 1.9-point gap measured on November 3, on 44 tasks. With refusal it scored 1.9 points below (0.0 to 3.7). That gap was 1.0 points larger than with the cut (0.8 smaller to 2.8 larger), not a measurable change. About a quarter of fetches returned an error. Each task’s source article and the benchmark’s own paper and dataset were filtered out.

948 * **How scored:** Claude Opus 4.6 judges under the benchmark’s rubric protocol; the original uses a different judge, and an Anthropic judge may favor the house style. Scores are means over the 44 tasks that every setting answered and the judge fully graded. The other six: four biology tasks that Claude Sonnet 5.5 answered in every run, and on which the safety classifiers stopped every attempt of Claude Fable 5.1 (36) and 11 of Claude Opus 5.5’s 12; one task, a survey of computer security research, on which the classifiers stopped one attempt of Claude Fable 5.1 at `low` and two of Claude Fable 5.2’s three at `high`; and one on which a safety check that Anthropic adds to its own evaluations stopped one attempt of Claude Sonnet 5.5.

949 * **Scores:** On the 44 tasks, and on all 50, with a refused or stopped attempt counted as 0 and one answered attempt that the judge did not fully grade kept at its partial score: Claude Sonnet 5.5, 57.2% and 56.8%; Claude Opus 5.5, 59.6% and 54.6%; Claude Fable 5.1, 60.2% and 54.7% at `low`, 62.1% and 56.6% at `medium`, and 62.5% and 57.0% at `high`. Claude Fable 5.2, on the 44 tasks: 54.5% at `low`, 55.0% at `medium`, and 57.7% at `high`. Task-by-task differences on the 44 tasks, taken before rounding, with 95% intervals: Claude Fable 5.1 at `high` over `low`, 2.3 points (1.3 to 3.3); Claude Opus 5.5 over Claude Sonnet 5.5, 2.4 (1.0 to 3.8); Claude Fable 5.1 at `high` over Claude Opus 5.5, 2.8 (1.4 to 4.3), and over Claude Sonnet 5.5, 5.2 points (4.0 to 6.5); Claude Fable 5.1 at `medium` over `low`, 1.9 (0.6 to 3.1); Claude Fable 5.2 at `high` over `low`, 3.3 (1.7 to 4.9), and at `medium` over `low`, 0.6 (-0.6 to 1.8); Claude Fable 5.2 at `high` over Claude Sonnet 5.5, 0.5 (-1.2 to 2.2), and over Claude Opus 5.5, -1.9 (-3.6 to -0.2); Claude Fable 5.2 over Claude Fable 5.1, -5.8 (-8.0 to -3.5) at `low`, -7.0 (-9.3 to -4.8) at `medium`, and -4.7 (-6.4 to -3.1) at `high`. On all 50 tasks: Claude Opus 5.5 over Claude Sonnet 5.5, -2.2 (-7.6 to 3.2); Claude Fable 5.1 at `high` over Claude Sonnet 5.5, 0.2 (-5.5 to 5.9).

950 * **How priced:** Each cost per task is the model’s own tokens at list prices, from the attempts’ usage records, over all 50 tasks and every attempt, averaged over the three runs: $1.11 USD on Claude Sonnet 5.5, $1.61 USD on Claude Opus 5.5, and $3.55 USD, $4.44 USD, and $5.69 USD on Claude Fable 5.1. Claude Fable 5.2’s costs are over its 46 tasks: $1.49 USD, $2.16 USD, and $4.82 USD; over the same 46 tasks the other five settings cost $1.13 USD, $1.69 USD, $3.85 USD, $4.82 USD, and $6.18 USD. On the four biology tasks, each Claude Fable 5.1 attempt was stopped at its first request, and attempts cost about a cent on average on Claude Fable 5.1 and $0.74 USD on Claude Opus 5.5. On the 44 tasks alone the costs are $1.13 USD, $1.68 USD, $3.85 USD, $4.77 USD, and $6.10 USD, and $1.50 USD, $2.20 USD, and $4.86 USD on Claude Fable 5.2. The cost comparisons in [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task) (1.5, 4.3, and 2.9 times; 61%, 54%, and 20% less than Claude Fable 5.1 at `low`, `medium`, and `high`) and in [Tune effort](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#tune-effort) (3.2 times) are on those 44 tasks, like the scores beside them. Costs cover model tokens only; the harness’s tools add no charges. The agent made 12 to 33 searches per task, refused attempts counted.

951 * **Charts:** The caching chart and the effort chart show runs from October 22, 2026, of Claude Fable 5.1, Claude Opus 5.5, and Claude Sonnet 5.5 at the same effort levels. The caching chart re-prices those runs’ requests with every input token at the uncached rate. The evaluation harness set the cache breakpoints.

950952 * **Comparability:** These scores are not comparable with the benchmark’s leaderboard.

951953

9529548. **Internal defect-search benchmark:**

953955

954 * **What was measured:** Anthropic-internal, for work larger than one context window: a corpus of about 22 million tokens from 14 public Python package sources, in 201 parts, with 130 planted defects and deterministic grading. Ten runs per configuration, on [Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview): 51 of the 120 on October 27 to 29, 2026, and 69 on November 2 to 3, 2026.

955 * **Configurations:** Alone, each model ran one session per part, each session given the findings so far: Claude Fable 5.1 and Claude Opus 5.5 at `low`, `medium`, and `high`, and Claude Sonnet 5.5 and Claude Haiku 5.5 at each model’s default (`high` and `medium`). With subagents, Claude Fable 5.1 or Claude Opus 5.5 ran at `high` as the orchestrator, through [multiagent orchestration](https://platform.claude.com/docs/en/managed-agents/multiagent-orchestration) (the `multiagent_20261001` type): one predefined agent as the subagent, at its model’s default effort, called once for each part, up to 25 at a time, with inline agents and dynamic workflows turned off. Every configuration ended with one more session, without subagents, that assembled the findings. Thinking ran at the platform’s default: on, with the model choosing when to think.

956 * **What was measured:** Anthropic-internal, for work larger than one context window: a corpus of about 22 million tokens from 14 public Python package sources, in 201 parts, with 130 planted defects and deterministic grading. Ten runs per configuration, on [Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview): 51 of the 170 on October 27 to 29, 2026, 69 on November 2 to 3, 2026, and Claude Fable 5.2’s 50 on November 3 to 4, 2026, before its release.

957 * **Configurations:** Alone, each model ran one session per part, each session given the findings so far: Claude Fable 5.2, Claude Fable 5.1, and Claude Opus 5.5 at `low`, `medium`, and `high`, and Claude Sonnet 5.5 and Claude Haiku 5.5 at each model’s default (`high` and `medium`). With subagents, Claude Fable 5.2, Claude Fable 5.1, or Claude Opus 5.5 ran at `high` as the orchestrator, through [multiagent orchestration](https://platform.claude.com/docs/en/managed-agents/multiagent-orchestration) (the `multiagent_20261001` type): one predefined agent as the subagent, at its model’s default effort, called once for each part, up to 25 at a time, with inline agents and dynamic workflows turned off. Every configuration ended with one more session, without subagents, that assembled the findings. Thinking ran at the platform’s default: on, with the model choosing when to think.

956958 * **Tools:** Every agent used the benchmark’s own shell and file tools, in an isolated virtual machine. Before any agent started, the evaluation removed installed copies of the corpus’s packages from that machine and checked that no connection from it succeeded.

957 * **Results:** Mean F1 (range) and mean cost per run. Claude Haiku 5.5 alone: 0.577 (0.550 to 0.606), $25 USD. Claude Sonnet 5.5 alone: 0.760 (0.669 to 0.788), $103 USD. Claude Opus 5.5 alone at `low`: 0.489 (0.437 to 0.551), $38 USD; at `medium`: 0.827 (0.797 to 0.850), $200 USD; at `high`: 0.850 (0.829 to 0.876), $236 USD. Claude Fable 5.1 alone at `low`: 0.829 (0.807 to 0.841), $527 USD; at `medium`: 0.839 (0.817 to 0.856), $603 USD; at `high`: 0.847 (0.829 to 0.861), $716 USD. Claude Opus 5.5 with Claude Sonnet 5.5 subagents: 0.831 (0.814 to 0.850), $139 USD; with Claude Haiku 5.5 subagents: 0.677 (0.640 to 0.718), $47 USD. Claude Fable 5.1 with Claude Sonnet 5.5 subagents: 0.825 (0.812 to 0.858), $172 USD; with Claude Haiku 5.5 subagents: 0.687 (0.660 to 0.723), $88 USD. Among the configurations that score above 0.80, every pair of ranges overlaps. Differences in mean F1, with 95% intervals: Claude Opus 5.5 with Claude Sonnet 5.5 subagents scored 0.4 points higher than Claude Opus 5.5 alone at `medium` (1.1 lower to 1.9 higher), 1.9 lower than alone at `high` (0.6 to 3.2), and 7.1 higher than Claude Sonnet 5.5 alone (4.6 to 9.7). Alone, Claude Opus 5.5 scored 2.3 points higher at `high` than at `medium` (0.7 to 3.9). Claude Fable 5.1 alone scored 1.8 points lower at `low` than at `high` (0.8 to 2.8); at `high` it scored 2.0 points higher than Claude Opus 5.5 alone at `medium` (0.7 to 3.4) and 0.3 lower than Claude Opus 5.5 alone at `high` (1.5 lower to 1.0 higher). With Claude Sonnet 5.5 subagents, Claude Fable 5.1 scored 0.6 points lower than Claude Opus 5.5 (1.9 lower to 0.6 higher). The Claude Opus 5.5 pairing cost 31% less than Claude Opus 5.5 alone at `medium` and 41% less than alone at `high`. Alone, Claude Opus 5.5 cost 15% less at `medium` than at `high`. All seven of November’s runs of Claude Sonnet 5.5 alone scored below October’s three (0.669 to 0.775, compared with 0.783 to 0.788); the cause is not known, and every run counts. Claude Fable 5.1 with Claude Haiku 5.5 subagents cost $85.77 USD per run in October and $89.06 USD in November.

958 * **How priced:** The platform’s list cost of each run’s sessions: tokens with prompt caching, plus session runtime. Five of Claude Opus 5.5’s runs at `high` are priced only from their token counts, at 5-minute cache prices, because each ran partly with the 1-hour cache duration, whose cache writes cost more. The cost of an extra check on tool calls, part of the evaluation’s safety setup, is left out.

959 * **Results:** Mean F1 (range) and mean cost per run. Claude Haiku 5.5 alone: 0.577 (0.550 to 0.606), $25 USD. Claude Sonnet 5.5 alone: 0.760 (0.669 to 0.788), $103 USD. Claude Opus 5.5 alone at `low`: 0.489 (0.437 to 0.551), $38 USD; at `medium`: 0.827 (0.797 to 0.850), $200 USD; at `high`: 0.850 (0.829 to 0.876), $236 USD. Claude Fable 5.1 alone at `low`: 0.829 (0.807 to 0.841), $527 USD; at `medium`: 0.839 (0.817 to 0.856), $603 USD; at `high`: 0.847 (0.829 to 0.861), $716 USD. Claude Fable 5.2 alone at `low`: 0.866 (0.852 to 0.884), $357 USD; at `medium`: 0.877 (0.863 to 0.884), $378 USD; at `high`: 0.909 (0.896 to 0.925), $563 USD. Claude Opus 5.5 with Claude Sonnet 5.5 subagents: 0.831 (0.814 to 0.850), $139 USD; with Claude Haiku 5.5 subagents: 0.677 (0.640 to 0.718), $47 USD. Claude Fable 5.1 with Claude Sonnet 5.5 subagents: 0.825 (0.812 to 0.858), $172 USD; with Claude Haiku 5.5 subagents: 0.687 (0.660 to 0.723), $88 USD. Claude Fable 5.2 with Claude Sonnet 5.5 subagents: 0.833 (0.795 to 0.856), $165 USD; with Claude Haiku 5.5 subagents: 0.716 (0.683 to 0.773), $85 USD. Among the other models’ configurations that score above 0.80, every pair of ranges overlaps. Differences in mean F1, with 95% intervals: Claude Opus 5.5 with Claude Sonnet 5.5 subagents scored 0.4 points higher than Claude Opus 5.5 alone at `medium` (1.1 lower to 1.9 higher), 1.9 lower than alone at `high` (0.6 to 3.2), and 7.1 higher than Claude Sonnet 5.5 alone (4.6 to 9.7). Alone, Claude Opus 5.5 scored 2.3 points higher at `high` than at `medium` (0.7 to 3.9). Claude Fable 5.1 alone scored 1.8 points lower at `low` than at `high` (0.8 to 2.8); at `high` it scored 2.0 points higher than Claude Opus 5.5 alone at `medium` (0.7 to 3.4) and 0.3 lower than Claude Opus 5.5 alone at `high` (1.5 lower to 1.0 higher). With Claude Sonnet 5.5 subagents, Claude Fable 5.1 scored 0.6 points lower than Claude Opus 5.5 (1.9 lower to 0.6 higher). Against Claude Opus 5.5 alone at `medium` and at `high`, Claude Fable 5.2 alone scored higher at each level, differences taken before rounding: at `low`, by 3.9 points (2.4 to 5.3) and 1.6 (0.3 to 2.9), for 1.8 and 1.5 times the cost; at `medium`, by 5.0 (3.6 to 6.3) and 2.7 (1.5 to 3.8), for 1.9 and 1.6 times; at `high`, by 8.2 (6.8 to 9.6) and 5.9 (4.7 to 7.1), for 2.8 and 2.4 times. It scored higher than Claude Fable 5.1 alone at the same level: by 3.6 points at `low` (2.6 to 4.7), 3.8 at `medium` (2.8 to 4.8), and 6.1 at `high` (5.3 to 7.0), for 32%, 37%, and 21% less. It scored 4.3 points lower at `low` than at `high` (3.3 to 5.3), for 37% less. With Claude Sonnet 5.5 subagents, Claude Fable 5.2 scored 0.2 points higher than Claude Opus 5.5 (1.3 lower to 1.7 higher), for 19% more, and scored 3.2 points lower than Claude Fable 5.2 alone at `low` (1.8 to 4.7), 4.3 lower than at `medium` (3.0 to 5.7), and 7.5 lower than at `high` (6.1 to 9.0), for 54%, 56%, and 71% less. One run of Claude Fable 5.2 alone at `high` ended early, without a score, and was replaced. The Claude Opus 5.5 pairing cost 31% less than Claude Opus 5.5 alone at `medium` and 41% less than alone at `high`. Alone, Claude Opus 5.5 cost 15% less at `medium` than at `high`. All seven of November’s runs of Claude Sonnet 5.5 alone scored below October’s three (0.669 to 0.775, compared with 0.783 to 0.788); the cause is not known, and every run counts. Claude Fable 5.1 with Claude Haiku 5.5 subagents cost $85.77 USD per run in October and $89.06 USD in November.

960 * **How priced:** The platform’s list cost of each run’s sessions: tokens with prompt caching, plus session runtime. Five of Claude Opus 5.5’s runs at `high` are priced only from their token counts, at 5-minute cache prices, because each ran partly with the 1-hour cache duration, whose cache writes cost more. Claude Fable 5.2’s own tokens are priced from their counts, at list prices with 5-minute cache writes; in its runs alone, the runtime of its sessions, under 0.2% of a run’s cost, is left out. The cost of an extra check on tool calls, part of the evaluation’s safety setup, is left out.

959961

9609629. **GPQA Diamond:** Rein et al., “GPQA: A Graduate-Level Google-Proof Q\&A Benchmark,” 2023. The 198-question Diamond subset, model-graded against reference answers, advisor tokens metered per request. Claude Haiku 5.5 and Claude Sonnet 5.5, each alone and with a Claude Opus 5.5 advisor, and Claude Opus 5.5 alone ran two runs per configuration on October 7, 2026, all with [server-side fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback) off, at each model’s default effort, and with refusals counted as wrong. A platform safety check refused one biology question per run on Claude Haiku 5.5 and Claude Sonnet 5.5 alone, one in two runs on Haiku 5.5 with the advisor, none on Sonnet 5.5 with the advisor, and six per run on Opus 5.5, which scored 91% with them counted as wrong and 93.5% on the questions it answered. Claude Haiku 5.5 alone scored 85%, 6 points below Opus 5.5. The advisor configurations added the tool without a prompt asking for consultations, and neither executor called the advisor on any question. The pairings scored 0.5 points (Claude Haiku 5.5) and 1.0 points (Claude Sonnet 5.5) above the executor alone, both within run-to-run noise.

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968970 * **How priced:** Costs are per attempt. Costs are priced as a customer’s organization is metered: each agent-loop request’s prior prompt as a cache read and its new tokens as a 5-minute cache write, from the runs’ own usage records, and each advisor call, which uses no cache, from its recorded tokens, all at list prices.

969971 * **Claude Opus 5.5 alone:** Claude Opus 5.5 alone ran on all 370 tasks, September 19 to 20, 2026: at its default effort (`medium`) and at `high` with five attempts per task, and at `low` and `xhigh` with one (369 of 370 scored at each, after a setup-check failure). Claude Opus 5.5 alone solved 74.8% of attempts at `low` for $0.35 USD per attempt, 86.6% at `medium` for $0.84 USD, 88.4% at `high` for $1.38 USD, and 91.1% at `xhigh` for $4.11 USD.

970972 * **Claude Opus 5.5 with a Claude Fable 5.1 advisor, runs:** The Claude Opus 5.5 executor at `high` with the released Claude Fable 5.1 as advisor (the August runs used a pre-release snapshot) ran five attempts per task on the same dates; one task failed its setup check, so 1,845 attempts were scored. The 279 attempts in which the advisor was turned away under load were re-run, and attempts whose consults timed out were kept, as in August.

971 * **Claude Fable 5.1 alone:** For comparison, the released Claude Fable 5.1 alone at `high`, its default, scored 85.7% (317 of 370 tasks), one attempt per task on October 7, 2026.

973 * **Claude Fable 5.1 and Claude Fable 5.2 alone:** For comparison, the released Claude Fable 5.1 alone at `high`, its default, scored 85.7% (317 of 370 tasks), one attempt per task on October 7, 2026. Claude Fable 5.2 alone ran on all 370 tasks, one attempt per task at `low`, `medium`, and `high` (369 of 370 scored at `medium`, after a setup-check failure).

972974 * **Consultations:** The August pairing averaged about two advisor consultations per attempt; the Claude Opus 5.5 pairing requested 1.39 and received 1.35.

973975 * **Claude Opus 5.5 with a Claude Fable 5.1 advisor, results:** The Claude Opus 5.5 pairing scored 90.1% at $2.92 USD per attempt: compared with Claude Opus 5.5 at its default, `medium`, that is 3.5 points for about 3.5 times the money. The latency cost is the consultations themselves: about one or two extra frontier-model calls per task, each on the task’s critical path. With the Claude Opus 5.5 executor, the advice saved almost no executor cost: $1.36 USD per attempt compared with $1.38 USD for Claude Opus 5.5 alone at `high`, while the consultations cost $1.55 USD.

974976 * **August pairing:** In August, with a Claude Opus 5 executor and a Claude Fable 5.1 advisor, the executor spent $1.26 USD less per attempt than Claude Opus 5 alone at its default, and the consultations cost $2.47 USD, so that saving paid for about half of the advice. That August pairing was the most accurate configuration measured at the time, at $6.21 USD per attempt.

975977 * **Claude Sonnet 5.5 alone, runs:** Claude Sonnet 5.5 alone ran on all 370 tasks on September 24, 2026, at its default effort (`high`) and at `medium`, one attempt per task, with the same 128,000-token output cap, which cut off none of its attempts. All 370 were scored at `medium`, and 369 of 370 at `high`, after a setup-check failure. Its costs are priced as a customer’s organization is metered.

976978 * **Claude Sonnet 5.5 alone, results:** With no advisor, Claude Sonnet 5.5 scored 77.8% at its default, `high`, for $0.33 USD per attempt, about 9 points below Claude Opus 5.5 at its default for about two fifths of the cost; at `medium`, it scored 62.7% for $0.16 USD. At `medium`, Claude Sonnet 5.5 scored about 15 points lower than at its default, `high`, for about 48% of the cost per attempt.

977 * **Compare models:** In [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task), Claude Opus 5.5 at its default cost under a third as much per attempt as Claude Fable 5.1 at `medium`, which is a single run.

979 * **Compare models:** In [Compare models](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#compare-models-on-cost-per-task), Claude Opus 5.5 at its default cost under two thirds as much per attempt as Claude Fable 5.2 at `medium`, which is a single run. At `low`, Fable 5.2 also scored 88.9% for $1.05 USD per attempt. At `high`, its default on the Messages API, it scored 93.5% for $5.39 USD per attempt.

978980

97998112. **Internal repository-task benchmark (cap measurement):**

980982

981 * **What was measured:** A separate Anthropic-internal set of about 130 repository tasks, run August 20, 2026 (Claude Fable 5.1) and September 19, 2026 (Claude Opus 5.5, at its default effort, `medium`), with a plain API agent loop, one attempt per task.

983 * **What was measured:** A separate Anthropic-internal set of about 130 repository tasks, run August 20, 2026 (Claude Fable 5.1) and September 19, 2026 (Claude Opus 5.5, at its default effort, `medium`), with a plain API agent loop, one attempt per task. The Claude Fable 5.2 runs used the same loop, one attempt per task; in them, as in the Claude Opus 5.5 runs, a turn that reached the cap ended its attempt.

982984 * **How priced:** Cost per solved task is priced as a customer is billed, with a 5-minute prompt cache, for Claude Fable 5.1, and at list prices from the token counts its runs recorded for Claude Opus 5.5.

983 * **Claude Fable 5.1 runs:** The Claude Fable 5.1 runs are 135 tasks per cap at the default effort set explicitly: the 16,384-token figure averages two runs (36.3% on both); the 64,000 and 128,000 figures are single runs (58.5% and 60.0%). Five problems drew a safety refusal in all four runs and count as failures.

985 * **Claude Fable 5.1 and Claude Fable 5.2 runs:** The Claude Fable 5.1 runs are 135 tasks per cap at the default effort set explicitly. The Claude Fable 5.2 runs are 134 tasks per cap at `high`, its default on the Messages API, set explicitly; one task was withdrawn from the set after the Claude Fable 5.1 and Claude Opus 5.5 runs. One further task failed the benchmark’s own check of its reference solution before the model started, in every run, so it is left out and 133 tasks are scored per cap. The 16,384-token figure averages two runs (19.5% and 21.1%); the 64,000 and 128,000 figures are single runs (77.4% and 78.2%). At 64,000, one task failed that check on its first run and was run again; it passed the check and is scored. No Fable 5.2 attempt at 16,384 or 64,000 drew a safety refusal. At 128,000, one attempt drew a safety refusal and one was stopped by a safety monitor in the evaluation environment before it finished; both count as failures. The changes the stopped attempt had made by then passed the tests; leaving it out would give 78.8% at 128,000. The Claude Fable 5.2 and Claude Opus 5.5 costs in the table price each attempt’s recorded token usage at the model’s list prices. The two models’ results were scored by different versions of the benchmark’s grading code.

984986 * **Claude Opus 5.5 runs:** The Claude Opus 5.5 16,384-token figure averages two runs (134 and 135 tasks scored), and its 64,000 and 128,000 figures are single runs (135 tasks each); two attempts in each 16,384-token run and one in each of the 64,000- and 128,000-token runs ended in a safety refusal and count as failures. Claude Opus 5.5 solved 57.6% at 16,384 (58.2% and 57.0%), 75.6% at 64,000, and 68.9% at 128,000. None of its attempts was cut off at 64,000 or 128,000, so the cap does not explain the difference between those two runs.

985 * **Attempts the cap ended:** Only 1 of the 66 Claude Opus 5.5 attempts that the 16,384-token cap ended, and 9 of the 117 Claude Fable 5.1 attempts, still passed.

986 * **Cost per attempt:** Cost per attempt was $3 USD at 16,384 and $4 USD at 64,000 for Claude Opus 5.5, at list prices, and $8 USD and $13 USD for Claude Fable 5.1, as a customer is billed.

987 * **Attempts the cap ended:** Only 1 of the 66 Claude Opus 5.5 attempts that the 16,384-token cap ended, and 9 of the 117 Claude Fable 5.1 attempts, still passed. So did 20 of the 226 Claude Fable 5.2 attempts.

988 * **Cost per attempt:** Cost per attempt was $3 USD at 16,384 and $4 USD at 64,000 for Claude Opus 5.5, at list prices, and $8 USD and $13 USD for Claude Fable 5.1, as a customer is billed. It was $6 USD and $19 USD for Claude Fable 5.2, at list prices.

987989 * **SWE-bench Pro cap figures:** The SWE-bench Pro cap figures are one Claude Fable 5.1 run per cap at the default effort, run August 26, 2026, on a 100-problem subset stratified from reference 3’s 482-problem set, not comparable to its scores; at the default effort the runs at 16,384 and at 64,000 each solved 94 of the 100 problems.

988 * **Turn length:** The per-turn distributions in the section’s dot plot come from the Claude Opus 5.5 and Claude Fable 5.1 runs at 128,000: no Opus 5.5 turn reached the cap (the longest was about 61,000 tokens, and 0.56% of its turns exceeded 16,384), and one Fable 5.1 turn reached 128,000 (0.46% of its turns exceeded 16,384). With the cap at 128,000, 2 of Claude Fable 5.1’s 14,331 turns were longer than 64,000 tokens, and no Claude Opus 5.5 turn was.

990 * **Turn length:** The per-turn distributions in the section’s dot plot come from the Claude Opus 5.5 and Claude Fable 5.1 runs at 128,000: no Opus 5.5 turn reached the cap (the longest was about 61,000 tokens, and 0.56% of its turns exceeded 16,384), and one Fable 5.1 turn reached 128,000 (0.46% of its turns exceeded 16,384). With the cap at 128,000, 2 of Claude Fable 5.1’s 14,331 turns were longer than 64,000 tokens, and no Claude Opus 5.5 turn was. With the cap at 128,000, 303 of Claude Fable 5.2’s 17,750 turns (1.7%) were longer than 16,384 tokens and 7 were longer than 64,000, counting the turns of attempts that were canceled and run again.

989991

99099213. **Chartography:** Surge AI, “Chartography,” 2026.

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10481050 * **Compaction trigger on Claude Haiku 5.5:** Measured October 21, 2026, on the Messages API with [compaction at a token threshold](https://platform.claude.com/docs/en/build-with-claude/compaction-threshold), no tools, adaptive thinking, the default effort (`medium`), the 5-minute cache, a cache breakpoint on the system prompt, and [automatic caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching#automatic-caching). Each session was one conversation of 45 requests: a 5,000-token system prompt, 10,000 tokens of filler text with every user turn, and one-word assistant turns, except that a reply with a compaction block was sent back whole. Four settings ran three sessions each: triggers of 150,000 tokens (the default), 90,000, and 50,000 (the lowest allowed), and no compaction. Costs within a setting agreed to within 4%. With the default trigger, 15 of each session’s 45 replies and all 3 summaries had prompts over 100,000 tokens. With a trigger of 90,000, the largest prompt held 97,269 tokens. Compaction ran at the first request whose whole prompt had reached the trigger, counting the system prompt, cache reads, and cache writes. The summary was written from that prompt plus 44 tokens, which together were up to 7,269 tokens over the trigger. Three more sessions, with a 22,000-token system prompt and a trigger of 50,000, showed that the system prompt counts. The summaries were short (184 to 640 output tokens) because the text was filler. The requests ran in one Anthropic-internal organization on the Claude API.

10491051 * **Compaction trigger on Claude Haiku 5.5, how priced:** From the `usage` fields at list prices, a session cost $0.272 USD with the default trigger, $0.082 USD at 90,000, $0.075 USD at 50,000, and $0.729 USD with no compaction. Per request, from the request after the first compaction through the last compaction, the three triggers cost $0.00605 USD, $0.00181 USD, and $0.00166 USD. With every prompt at the prices for prompts up to 100,000 tokens, the default would cost $0.00206 USD per request, and a trigger of 90,000 would save 12%. A compaction’s summary and reply are each priced by their own prompt’s size.

10501052

105119. **Cache duration measurement on Claude Fable 5.1:** The same 20-issue triage job and harness as reference 16, with `max_tokens` raised to 4,096, run August 23 and August 26, 2026, on the Claude Fable 5.1 launch snapshot at its launch prices ($10 USD input, $12.50 USD 5-minute write, $20 USD 1-hour write, $0.25 USD cache read, $50 USD output per million tokens), three settings per schedule: the 5-minute cache, the 1-hour cache, and the 5-minute cache kept warm by a `max_tokens: 0` request on the unchanged prefix every 4 minutes, timed from the previous request’s start (the August 23 runs sent keep-alive requests with `max_tokens: 1`; in the August 26 cells reported here, every answered keep-alive request refreshed the cache and its response reported no output tokens). Schedules: no pauses, 10% of turns, and every turn at 6 minutes on all 20 issues, and 45-minute pauses on the 5-issue subset; three runs per cell (six for the August 26 keep-alive cell with 45-minute pauses), cost computed from each response’s `usage` fields at list prices, accuracy against the same gold labels (12 to 18 exact labels of 20). Per-session means on August 26 for the 5-minute, 1-hour, and keep-alive settings: no pauses $2.42 USD, $3.09 USD, $2.29 USD; 10% paused $4.50 USD, $2.96 USD, $2.36 USD; every turn $22.89 USD, $3.01 USD, $2.62 USD; the August 23 cells agree within 6%. The 45-minute figures ($1.68 USD, $0.59 USD, and $0.71 USD per 5-issue session) are from later sessions of August 26: that day’s first set of sessions was cut off when its machine was shut down, and the second was affected by a fault in the service and is set aside. The third set gives the 5-minute and 1-hour figures; its three keep-alive sessions sent each keep-alive request once, lost requests to rate-limit refusals, and are not in the mean. The keep-alive figure is the mean of six further sessions that sent any refused keep-alive request again within two seconds. The August 23 runs gave $1.67 USD, $0.58 USD, and $0.70 USD. The break-even between the 5-minute and 1-hour settings is 3.1% of turns, the same measure as reference 16. Claude Fable 5.1’s cache read costs 0.025x the input price while its cache writes keep the standard multipliers, so a keep-alive request that re-reads the prefix is cheap and the 1-hour duration’s write premium is the larger bill, except with 45-minute pauses, where the keep-alive requests cost more than the premium.

105319. **Cache duration measurement on Claude Fable 5.1 and Claude Fable 5.2:** The same 20-issue triage job and harness as reference 16, with `max_tokens` raised to 4,096, run August 23 and August 26, 2026, on the Claude Fable 5.1 launch snapshot at its launch prices ($10 USD input, $12.50 USD 5-minute write, $20 USD 1-hour write, $0.25 USD cache read, $50 USD output per million tokens), three settings per schedule: the 5-minute cache, the 1-hour cache, and the 5-minute cache kept warm by a `max_tokens: 0` request on the unchanged prefix every 4 minutes, timed from the previous request’s start (the August 23 runs sent keep-alive requests with `max_tokens: 1`; in the August 26 cells reported here, every answered keep-alive request refreshed the cache and its response reported no output tokens). Schedules: no pauses, 10% of turns, and every turn at 6 minutes on all 20 issues, and 45-minute pauses on the 5-issue subset; three runs per cell (six for the August 26 keep-alive cell with 45-minute pauses), cost computed from each response’s `usage` fields at list prices, accuracy against the same gold labels (12 to 18 exact labels of 20). Per-session means on August 26 for the 5-minute, 1-hour, and keep-alive settings: no pauses $2.42 USD, $3.09 USD, $2.29 USD; 10% paused $4.50 USD, $2.96 USD, $2.36 USD; every turn $22.89 USD, $3.01 USD, $2.62 USD; the August 23 cells agree within 6%. The 45-minute figures ($1.68 USD, $0.59 USD, and $0.71 USD per 5-issue session) are from later sessions of August 26: that day’s first set of sessions was cut off when its machine was shut down, and the second was affected by a fault in the service and is set aside. The third set gives the 5-minute and 1-hour figures; its three keep-alive sessions sent each keep-alive request once, lost requests to rate-limit refusals, and are not in the mean. The keep-alive figure is the mean of six further sessions that sent any refused keep-alive request again within two seconds. The August 23 runs gave $1.67 USD, $0.58 USD, and $0.70 USD. The break-even between the 5-minute and 1-hour settings is 3.1% of turns, the same measure as reference 16. Claude Fable 5.1’s cache read costs 0.025x the input price while its cache writes keep the standard multipliers, so a keep-alive request that re-reads the prefix is cheap and the 1-hour duration’s write premium is the larger bill, except with 45-minute pauses, where the keep-alive requests cost more than the premium. Claude Fable 5.2 ran the same job at `high`, its default on the Messages API, and at list prices ($8 USD input, $10 USD 5-minute write, $16 USD 1-hour write, $0.20 USD cache read, $40 USD output per million tokens). Like the Claude Opus 5.5 cells in reference 16, it used a port of the harness that sends the same request bodies, with `max_tokens` raised to 4,096. Schedules: no pauses, 5% and 10% of turns, and every turn at 6 minutes on all 20 issues, and 20-minute and 45-minute pauses on the 5-issue subset, three runs per cell. The 45-minute cells were measured twice; their figures pool both sets of three sessions and, as with Claude Fable 5.1, leave out the keep-alive sessions that lost keep-alive requests (here, to timeouts; one in each set), so the 45-minute keep-alive figure is the mean of four sessions and the 5-minute and 1-hour figures the mean of six. Throughout, the keep-alive requests were sent with `max_tokens: 0`. The test client waits 30 seconds for a keep-alive request and does not retry. Across the schedules listed above, it stopped waiting for 3 of 886 keep-alive requests, all in the 45-minute cells, and each time the cache expired and the next keep-alive request wrote the prefix again. Per-session means for the 5-minute, 1-hour, and keep-alive settings: no pauses $2.18 USD, $2.66 USD, $2.23 USD; 10% paused $4.16 USD, $2.82 USD, $2.29 USD; every turn at 6 minutes $20.36 USD, $2.61 USD, $2.50 USD; and $1.43 USD, $0.53 USD, and $0.65 USD per 5-issue session with 45-minute pauses. The Claude Fable 5.2 savings in [Pick the cache duration](https://platform.claude.com/docs/en/about-claude/models/optimizing-for-cost-and-intelligence#pick-the-cache-duration) are taken before rounding. With the two sessions that lost keep-alive requests included, the 45-minute keep-alive mean was $0.73 USD, $0.20 USD more than the 1-hour setting.

10521054

1053105520. **Terminal-Bench 3:** the public terminal-agent benchmark’s 74 tasks, run on [Claude Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview) with two custom tools, a shell and a file editor that the evaluation harness runs in each task’s own container, in place of the platform’s built-in tools, and otherwise at the platform’s default settings for external accounts, two runs per model at `high` effort, August 27 to 28, 2026. These runs used Terminal-Bench version 3.0, and their scores are not comparable with the public Terminal-Bench leaderboard or with the Terminal-Bench 4.0 results in the Claude Opus 5.5 system card, which come from runs in Claude Code at `max` effort. Each task’s time limits are 2.5 times the benchmark’s own, which gives the agent between 75 minutes and 20 hours per task (5 hours for the median task), and each task gets three times the memory it specifies, from 6 GiB to 96 GiB, with extra memory for the 12 tasks that run helper services. The agent had no general internet access: its containers could reach an internal package mirror, a short list of download sites including GitHub and the Python Package Index, and a few sites specific to some tasks, and eight of the tasks had no network access at all. Scores are raw pass rates over the 148 attempts per model; single runs swing by 5 to 11 points. Costs are what a customer would be billed at list prices, re-priced request by request from the runs’ usage records with the 5-minute cache lifetime. Claude Opus 4.7, Claude Opus 4.8, and Claude Opus 5 each spend $8 USD to $15 USD per task. Claude Opus 4.7 ended 11 of its 148 attempts at its output cap.

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1414

1616| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :-------------------- | :-------------- | :-------------- | :----------------------- | :--------------------- |

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3739

38*1 Cache hits and refreshes on Claude Fable 5.1 and Claude Mythos 5.1 are priced at 0.025x the base input price.*

40*1 Cache hits and refreshes on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1 are priced at 0.025x the base input price.*

3941

4042*2 Cache hits and refreshes on Claude Opus 5.5 and Claude Sonnet 5.5 are priced at 0.05x the base input price.*

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142144

143145Prompt caching uses the following pricing multipliers relative to base input token rates:

144146

145| Cache operation | Multiplier | Duration |

146| -------------------- | ------------------------------------------------------------------------------------------------------------------------ | ------------------------------------ |

147| 5-minute cache write | 1.25x base input price | Cache valid for 5 minutes |

148| 1-hour cache write | 2x base input price | Cache valid for 1 hour |

149| Cache read (hit) | 0.1x base input price (0.025x on Claude Fable 5.1 and Claude Mythos 5.1; 0.05x on Claude Opus 5.5 and Claude Sonnet 5.5) | Same duration as the preceding write |

147| Cache operation | Multiplier | Duration |

148| -------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------ |

149| 5-minute cache write | 1.25x base input price | Cache valid for 5 minutes |

150| 1-hour cache write | 2x base input price | Cache valid for 1 hour |

151| Cache read (hit) | 0.1x base input price (0.025x on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1; 0.05x on Claude Opus 5.5 and Claude Sonnet 5.5) | Same duration as the preceding write |

150152

151Cache write tokens are charged when content is first stored. Cache read tokens are charged when a subsequent request retrieves the cached content. A cache hit costs 10 percent of the standard input price, which means caching pays off after one cache read for the 5-minute duration (1.25x write), or after two cache reads for the 1-hour duration (2x write). On Claude Fable 5.1 and Claude Mythos 5.1, a cache hit costs 2.5 percent of the standard input price ($0.25 USD per million tokens). On Claude Opus 5.5 and Claude Sonnet 5.5, a cache hit costs 5 percent of the standard input price ($0.20 USD per million tokens on Claude Opus 5.5, $0.10 USD on Claude Sonnet 5.5).

153Cache write tokens are charged when content is first stored. Cache read tokens are charged when a subsequent request retrieves the cached content. A cache hit costs 10 percent of the standard input price, which means caching pays off after one cache read for the 5-minute duration (1.25x write), or after two cache reads for the 1-hour duration (2x write). On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, and Claude Mythos 5.1, a cache hit costs 2.5 percent of the standard input price ($0.20 USD per million tokens on Claude Fable 5.2 and Claude Mythos 5.2, $0.25 USD on Claude Fable 5.1 and Claude Mythos 5.1). On Claude Opus 5.5 and Claude Sonnet 5.5, a cache hit costs 5 percent of the standard input price ($0.20 USD per million tokens on Claude Opus 5.5, $0.10 USD on Claude Sonnet 5.5).

152154

153155These multipliers stack with other pricing modifiers, including the Batch API discount and data residency.

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164166

165167### Fast mode pricing

166168

167[Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) provides significantly faster output for Claude Opus 5.5, Claude Opus 5, and Claude Opus 4.8 at premium pricing. Fast mode for Claude Opus 5 and Claude Opus 4.8 is in research preview. Fast mode pricing applies across the full context window, including requests over 200k input tokens. Fast mode is available on the Claude API (first-party). For Claude Opus 5.5, it is also available on [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed#billing) and on [Claude in Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) for deployments hosted on Azure.

169[Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) provides significantly faster output for Claude Fable 5.2, Claude Opus 5.5, Claude Opus 5, and Claude Opus 4.8 at premium pricing. Fast mode for Claude Opus 5 and Claude Opus 4.8 is in research preview. Fast mode pricing applies across the full context window, including requests over 200k input tokens. Fast mode is available on the Claude API (first-party). For Claude Opus 5.5, it is also available on [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed#billing) and on [Claude in Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) for deployments hosted on Azure.

168170

171Fast mode for Claude Fable 5.2 is also available on [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed#billing).

172

173Fast mode for Claude Fable 5.2 is also available on [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed). Google Cloud sets its prices there. See [Cloud platform pricing](https://platform.claude.com/docs/en/about-claude/pricing#cloud-platform-pricing).

174

175Fast mode is also available for Claude Mythos 5.2 on the Claude API. [Availability of fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode#feature-availability) lists every platform where Claude Mythos 5.2 has fast mode.

176

169177| Model | Input | Output |

170178| ------------------------------- | -------------- | -------------- |

179| Claude Fable 5.2 | $16 USD / MTok | $80 USD / MTok |

180| Claude Mythos 5.2 | $16 USD / MTok | $80 USD / MTok |

171181| Claude Opus 5.5 | $8 USD / MTok | $40 USD / MTok |

172182| Claude Opus 5 / Claude Opus 4.8 | $10 USD / MTok | $50 USD / MTok |

173183

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186196

187197| Model | Batch input | Batch output |

188198| :--------------------------------------------------------------------------------------------------------------------------------------------------------------------- | :----------- | :------------ |

199| Claude Fable 5.2 | $4 / MTok | $20 / MTok |

200| Claude Mythos 5.2 ([limited availability](https://support.claude.com/en/articles/14604842)) | $4 / MTok | $20 / MTok |

189201| Claude Fable 5.1 | $5 / MTok | $25 / MTok |

190202| Claude Mythos 5.1 ([limited availability](https://support.claude.com/en/articles/14604842)) | $5 / MTok | $25 / MTok |

191203| Claude Fable 5 | $5 / MTok | $25 / MTok |

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2626* **Streaming patterns:** Implementation details for building chat UIs and handling incremental display

2727* **Batch processing:** Offline batch processing at 50 percent cost

2828* **Prompt caching:** Prefix-stability design, breakpoint placement, and silent-invalidator audit

29* **Model migration:** Step-by-step guidance for migrating to newer Claude models (including the breaking changes and behavior shifts on [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-5), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide#migrating-from-claude-sonnet-5), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide), and [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/migration-guide))

29* **Model migration:** Step-by-step guidance for migrating to newer Claude models (including the breaking changes and behavior shifts on [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-5), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide#migrating-from-claude-sonnet-5), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide), and [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/migration-guide))

3030* **Preserved thinking migration:** Finding, measuring, and fixing the history edits that invalidate `thinking` blocks, available through the `/claude-api preserved-thinking-migration` subcommand

3131* **Current model information:** Model IDs, context window sizes, and pricing

3232* **Common pitfalls:** Detailed guidance on avoiding frequent mistakes when integrating with the API

from line 145

145145* **Effort calibration**, recommending an `output_config.effort` starting point for the target model (for example, the default `high` on Claude Opus 5, and `xhigh` for coding and agentic use cases on Claude Opus 4.8 and Claude Opus 4.7)

146146* **Prompt-behavior tuning**, flagging length-control, tool-triggering, subagent, and instruction-following prompts that might behave differently on the target model

147147* **Silent default handling**, opting back into thinking summarization (`thinking.display: "summarized"`) when reasoning is surfaced to users on Claude Opus 4.8 and Claude Opus 4.7

148* **Refusal fallback configuration**, adding `stop_reason: "refusal"` handling before reading response content and setting up a [fallback retry path](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback) when the target is Claude Fable 5.1, Claude Fable 5, Claude Opus 5.5, Claude Opus 5, or Claude Sonnet 5.5 (the server-side `fallbacks` parameter, typically in its `"default"` mode, the SDK refusal-fallback middleware, or a fallback-credit retry), and updating fallback code written against earlier preview shapes

148* **Refusal fallback configuration**, adding `stop_reason: "refusal"` handling before reading response content and setting up a [fallback retry path](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback) when the target is Claude Fable 5.2, Claude Fable 5.1, Claude Fable 5, Claude Opus 5.5, Claude Opus 5, or Claude Sonnet 5.5 (the server-side `fallbacks` parameter, typically in its `"default"` mode, the SDK refusal-fallback middleware, or a fallback-credit retry), and updating fallback code written against earlier preview shapes

149149

150150As it edits, the skill explains each change and its motivation inline. On completion, it produces a checklist of items that require manual verification (typically integration tests, length-control prompt tuning, and cost/rate-limit re-baselining).

151151

152For the full list of model-specific changes the skill applies, see [Migrating to Claude Opus 5.5 from Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-5), [Migrating to Claude Opus 5.5 from Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-4-8), [Migrating to Claude Sonnet 5.5 from Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide#migrating-from-claude-sonnet-5), [Claude Haiku 5.5 migration guide](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide), and [Claude Fable 5.1 and Claude Mythos 5.1 migration guide](https://platform.claude.com/docs/en/models/fable-5-1/migration-guide).

152For the full list of model-specific changes the skill applies, see [Migrating to Claude Opus 5.5 from Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-5), [Migrating to Claude Opus 5.5 from Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-5-5/migration-guide#migrating-from-claude-opus-4-8), [Migrating to Claude Sonnet 5.5 from Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5-5/migration-guide#migrating-from-claude-sonnet-5), [Claude Haiku 5.5 migration guide](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide), and [Claude Fable 5.2 and Claude Mythos 5.2 migration guide](https://platform.claude.com/docs/en/models/fable-5-2/migration-guide).

153153

154154## Checking an integration for preserved thinking

155155

agents-and-tools/mcp-connector Changed · +6 / -4 lines

from line 9

99 eligibility: not-eligible

1010 note: Data retained according to standard policy.

1111 supportedModels:

12 - claude-fable-5-2

13 - claude-mythos-5-2

1214 - claude-fable-5-1

1315 - claude-mythos-5-1

1416 - claude-fable-5

from line 1304

13021304 <Tabs>

13031305 <Tab title="Gradle">

13041306 ```kotlin

1305 implementation("com.anthropic:anthropic-java:3.6.0")

1306 implementation("com.anthropic:anthropic-java-mcp:3.6.0")

1307 implementation("com.anthropic:anthropic-java:3.7.0")

1308 implementation("com.anthropic:anthropic-java-mcp:3.7.0")

13071309 ```

13081310 </Tab>

13091311

from line 1314

13121314 <dependency>

13131315 <groupId>com.anthropic</groupId>

13141316 <artifactId>anthropic-java</artifactId>

1315 <version>3.6.0</version>

1317 <version>3.7.0</version>

13161318 </dependency>

13171319 <dependency>

13181320 <groupId>com.anthropic</groupId>

13191321 <artifactId>anthropic-java-mcp</artifactId>

1320 <version>3.6.0</version>

1322 <version>3.7.0</version>

13211323 </dependency>

13221324 ```

13231325 </Tab>

agents-and-tools/tool-use/advisor-tool Changed · +50 / -17 lines

from line 9

99 eligibility: eligible

1010 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements). Advisor model output is returned in the API response; nothing is stored server-side after the response.

1111 supportedModels:

12 - claude-fable-5-2

13 - claude-mythos-5-2

1214 - claude-fable-5-1

1315 - claude-mythos-5-1

1416 - claude-fable-5

from line 62

6062

6163The advisor fits these configurations:

6264

63* **You currently use Sonnet on complex tasks:** Add a higher-tier advisor. Opus keeps total cost similar or lower; Claude Fable 5.1 maximizes the quality lift.

65* **You currently use Sonnet on complex tasks:** Add a higher-tier advisor. Opus keeps total cost similar or lower; Claude Fable 5.2 maximizes the quality lift.

6466* **You currently use Haiku and want a step up in intelligence:** Add an Opus or Fable advisor. Expect higher cost than Haiku alone, but lower than switching the executor to a larger model.

6567

6668Results are task-dependent. Evaluate on your own workload.

from line 373

371373| `advisor_redacted_result` | `encrypted_content`, `stop_reason` | The advisor model returns encrypted output. |

372374

373375<Note>

374 Claude Sonnet 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Fable 5, Claude Mythos 5, and Claude Haiku 5.5 advisors return the encrypted `advisor_redacted_result`. Every other advisor model in [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) returns the plaintext `advisor_result`. To read the advice text in your own responses, use an advisor that returns plaintext, such as `claude-opus-4-8`, where [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) lists one for your executor. Claude Sonnet 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Fable 5, and Claude Mythos 5 executors pair only with advisors that return the encrypted form, so on those executors the advice text isn’t readable in the response.

376 Claude Fable 5.2, Claude Mythos 5.2, Claude Sonnet 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Fable 5, Claude Mythos 5, and Claude Haiku 5.5 advisors return the encrypted `advisor_redacted_result`. Every other advisor model in [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) returns the plaintext `advisor_result`. To read the advice text in your own responses, use an advisor that returns plaintext, such as `claude-opus-4-8`, where [Model compatibility](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) lists one for your executor. Claude Fable 5.2, Claude Mythos 5.2, Claude Sonnet 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Fable 5, and Claude Mythos 5 executors pair only with advisors that return the encrypted form, so on those executors the advice text isn’t readable in the response.

375377</Note>

376378

377379Here is the same request sent twice, identical except for the advisor `model` in the tool definition, showing both variants.

from line 408

406408

407409With `advisor_result`, the `text` field contains human-readable advice. With `advisor_redacted_result`, the `encrypted_content` field contains an opaque blob that you cannot read. In the next request, the server decrypts it and renders the plaintext into the executor’s prompt.

408410

409In both cases, round-trip the content verbatim in later requests. If you switch advisor models mid-conversation, branch on `content.type` to handle both shapes.

411In both cases, round-trip the content verbatim in later requests. If you switch advisor models mid-conversation, branch on `content.type` to handle both shapes. A switch is an edit to `tools`, so read [Multi-turn conversations](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#multi-turn-conversations) before you make one in a conversation that carries thinking blocks.

410412

411413### Error results

412414

from line 744

742744 ```

743745</CodeGroup>

744746

745You can drop the advisor tool from `tools` in a follow-up request while the message history still contains `advisor_tool_result` blocks, as long as no advisor call is [still pending](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#resuming-a-paused-turn). The API accepts the request and keeps the historical blocks, but the model cannot call the advisor in that request. You must still send the `advisor-tool-2026-03-01` beta header for those history blocks to be accepted.

747You can drop the advisor tool from `tools` in a follow-up request while the message history still contains `advisor_tool_result` blocks, as long as no advisor call is [still pending](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#resuming-a-paused-turn). The API accepts the request and keeps the historical blocks, but the model cannot call the advisor in that request. You must still send the `advisor-tool-2026-03-01` beta header for those history blocks to be accepted. That covers the `advisor_tool_result` blocks, not thinking blocks. Removing the advisor tool, or changing its `model` or `caching`, is an [edit to `tools`](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#what-counts-as-an-edit), and it invalidates the thinking blocks already in the history. Where the API enforces the [prefix check](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#prefix-check), the request then returns a 400 error. The API enforces it on every account when the executor is Claude Fable 5.2 or Claude Mythos 5.2, and for other executors wherever the table in [When `prefix_mismatch_behavior` is unset](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#enforcement) shows it. To drop those blocks and continue, set `thinking.block_binding.prefix_mismatch_behavior` to `"drop_block"` (beta, `thinking-binding-controls-2026-08-01` header) on that request and on every later request in the conversation.

746748

747749<Note>

748 The advisor tool has no built-in conversation-level cap. To limit advisor calls across a conversation, count them client-side. When you reach your ceiling, remove the advisor tool from your `tools` array. You do not need to strip `advisor_tool_result` blocks from your message history.

750 The advisor tool has no built-in conversation-level cap. To limit advisor calls across a conversation, count them client-side. When you reach your ceiling, remove the advisor tool from your `tools` array. You do not need to strip `advisor_tool_result` blocks from your message history. Where the prefix check is enforced, read the preceding paragraph first: the request returns a 400 error unless you set `"drop_block"`.

749751</Note>

750752

751753### Resuming a paused turn

from line 1263

12611263

12621264The plain-text nudge is highly salient on Claude Haiku 4.5 and Sonnet executors: 74 percent (Sonnet) to 98 percent (Claude Haiku 4.5) of nudged attempts in Anthropic’s testing called the advisor immediately at turn 2. If that lands before your executor has read the problem or gathered context, the resulting advisor call is low-context and can displace a better-timed later call. Measure your executor’s baseline first-call turn before adding the nudge. If the executor already calls the advisor reliably and its first call typically lands at turn N, set `NUDGE_TURN` greater than N. In Anthropic’s testing, a turn-2 nudge on workloads where the baseline first call was turn 7 or later correlated with a 3 to 4 percentage-point task-performance drop. On a browse workload where the baseline call rate was 86 percent, the same nudge raised engagement with no task-performance cost.

12631265

1264To force a consult on a specific request instead of nudging, set `tool_choice` to `{"type": "tool", "name": "advisor"}`, subject to the constraints in [Forcing tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools#forcing-tool-use). Forcing tool use cannot be combined with manual extended thinking (`thinking: {type: "enabled"}`): the API returns a `400 invalid_request_error` if you enable both. Adaptive thinking supports forced tool use. Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and Claude Mythos 5.1 executors reject `tool_choice` types `tool` and `any`, so use the prompt nudge on those models instead.

1266To force a consult on a specific request instead of nudging, set `tool_choice` to `{"type": "tool", "name": "advisor"}`, subject to the constraints in [Forcing tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/define-tools#forcing-tool-use). Forcing tool use cannot be combined with manual extended thinking (`thinking: {type: "enabled"}`): the API returns a `400 invalid_request_error` if you enable both. Adaptive thinking supports forced tool use. Claude Fable 5.2, Claude Mythos 5.2, Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and Claude Mythos 5.1 executors reject `tool_choice` types `tool` and `any`, so use the prompt nudge on those models instead.

12651267

12661268## Streaming

12671269

from line 1424

14221424

14231425**When to enable it:** The cache write costs more than the reads save when the advisor is called two or fewer times in each conversation. Caching breaks even at roughly three advisor calls and improves from there. Enable it for long agent loops, and keep it off for short tasks.

14241426

1425**Keep it consistent:** Set `caching` once and leave it for the whole conversation. Toggling it off and on mid-conversation causes cache misses.

1427**Keep it consistent:** Set `caching` once and leave it for the whole conversation. Toggling it off and on mid-conversation causes cache misses. Where the prefix check is enforced, the toggle is also an edit to `tools`, and the next request returns a 400 error unless you set `"drop_block"`, as [Multi-turn conversations](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#multi-turn-conversations) explains.

14261428

14271429<Warning>

14281430 [`clear_thinking`](https://platform.claude.com/docs/en/build-with-claude/context-editing) with a `keep` value other than `"all"` shifts the advisor’s quoted transcript each turn, causing advisor-side cache misses. This is a cost degradation only. Advice quality is unaffected. When thinking is on without explicit `clear_thinking` configuration, the API defaults to `keep: {type: "thinking_turns", value: 1}`, which triggers this behavior (the default on earlier Opus and Sonnet models and on Haiku models through Claude Haiku 4.5, whereas on Claude Opus 4.5 and later Opus models, Claude Sonnet 4.6 and later Sonnet models, and Claude Haiku 5.5, the default is to keep all turns). Set `keep: "all"` to preserve advisor cache stability.

from line 1828

18261828

18271829### Cost control

18281830

1829* For conversation-level budgets, count advisor calls client-side. When you reach your cap, remove the advisor tool from `tools`; you do not need to strip `advisor_tool_result` blocks from your message history (see the note in [Multi-turn conversations](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#multi-turn-conversations)).

1831* For conversation-level budgets, count advisor calls client-side. When you reach your cap, remove the advisor tool from `tools`; you do not need to strip `advisor_tool_result` blocks from your message history (see the note in [Multi-turn conversations](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#multi-turn-conversations)). Where the API enforces the prefix check, the request that removes the tool returns a 400 error unless you set `prefix_mismatch_behavior` to `"drop_block"`, as that section explains. The API enforces the check for every account when the executor is Claude Fable 5.2 or Claude Mythos 5.2.

18301832* Enable `caching` only for conversations where you expect three or more advisor calls.

18311833

18321834## Model compatibility

from line 1835

18331835

18341836The executor model (the top-level `model` field) and the advisor model (the `model` field inside the tool definition) must form a valid pair. The advisor must be Claude Sonnet 4.6 or a more capable model, and it must be at least as capable as the executor. Models of equal capability (for example, Claude Opus 4.7 and Claude Opus 4.8) can advise each other.

18351837

1836**[Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) & [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview)** — *For demanding reasoning and long-horizon agentic work*

1838**[Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) & [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview)** — *For demanding reasoning and long-horizon agentic work*

18371839

18381840**Supported advisor models**

18391841

1840* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

1841* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

1842* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1843* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18421844

18431845**[Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview)** — *For long-running agentic coding and knowledge work*

18441846

18451847**Supported advisor models**

18461848

1849* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1850* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18471851* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

18481852* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

18491853* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1859

18551859

18561860**Supported advisor models**

18571861

1862* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1863* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18581864* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

18591865* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

18601866* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1873

18671873

18681874**Supported advisor models**

18691875

1876* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1877* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18701878* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

18711879* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

18721880* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1887

18791887* [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview) (claude-sonnet-5)

18801888* [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview) (claude-haiku-5-5)

18811889

1890**[Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) & [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview)**

1891

1892**Supported advisor models**

1893

1894* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1895* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

1896* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

1897* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

1898

18821899**[Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview) & [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview)**

18831900

18841901**Supported advisor models**

18851902

1903* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1904* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18861905* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

18871906* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

18881907* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1913

18941913

18951914**Supported advisor models**

18961915

1916* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1917* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

18971918* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

18981919* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

18991920* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1926

19051926

19061927**Supported advisor models**

19071928

1929* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1930* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19081931* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19091932* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19101933* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1942

19191942

19201943**Supported advisor models**

19211944

1945* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1946* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19221947* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19231948* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19241949* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1958

19331958

19341959**Supported advisor models**

19351960

1961* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1962* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19361963* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19371964* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19381965* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1977

19501977

19511978**Supported advisor models**

19521979

1980* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1981* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19531982* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19541983* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19551984* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 1995

19661995

19671996**Supported advisor models**

19681997

1998* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

1999* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19692000* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19702001* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19712002* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 2015

19842015

19852016**Supported advisor models**

19862017

2018* [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview) (claude-mythos-5-2)

2019* [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) (claude-fable-5-2)

19872020* [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) (claude-mythos-5-1)

19882021* [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) (claude-fable-5-1)

19892022* [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview) (claude-mythos-5)

from line 2072

20392072* Availability: Available

20402073* Usage: Add an advisor tool (type `advisor_20260301`) with the advisor model to the request’s `tools`. It takes `max_uses`, `max_tokens` and caching options.

20412074

2042| Status | Cloud platforms | Models |

2043| ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2044| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

2075| Status | Cloud platforms | Models |

2076| ------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2077| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

20452078

20462079#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

20472080

from line 2081

20482081* Availability: Available

20492082* Usage: Set `advisor` to `{"type": "enabled", "model": …}` in the agent’s `multiagent` block. There are no `max_uses`, `max_tokens` or caching options, and advice arrives as thread events on the session’s event stream.

20502083

2051| Status | Cloud platforms | Models |

2052| ------ | ------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2053| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

2084| Status | Cloud platforms | Models |

2085| ------ | ------------------------------------------------------------------------------------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2086| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

20542087

20552088### Required beta headers

20562089

agents-and-tools/tool-use/browser-use-sdk Changed · +7 / -4 lines

from line 5

55featureMetadata:

66 status: beta

77 supportedModels:

8 - claude-fable-5-2

9 - claude-mythos-5-2

810 - claude-fable-5-1

911 - claude-mythos-5-1

1012 - claude-fable-5

from line 1389

13871389

13881390* Availability: Available

13891391

1390| Status | Cloud platforms | Models |

1391| ------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1392| Beta | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1393| Beta | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1392| Status | Cloud platforms | Models |

1393| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1394| Beta | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1395| Beta | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1396| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

13941397

13951398#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

13961399

agents-and-tools/tool-use/browser-use-tool Changed · +7 / -4 lines

from line 8

88 eligibility: eligible

99 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements). Client-side tool. Anthropic does not run browser actions or retain page content beyond standard API handling.

1010 supportedModels:

11 - claude-fable-5-2

12 - claude-mythos-5-2

1113 - claude-fable-5-1

1214 - claude-mythos-5-1

1315 - claude-fable-5

from line 1623

16211623

16221624* Availability: Available

16231625

1624| Status | Cloud platforms | Models |

1625| --------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1626| Available | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1627| Available | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1626| Status | Cloud platforms | Models |

1627| --------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1628| Available | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1629| Available | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

1630| Available | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

16281631

16291632#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

16301633

agents-and-tools/tool-use/computer-use-tool Changed · +10 / -7 lines

from line 8

88 eligibility: eligible

99 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements). Client-side tool where screenshots and files are captured and stored in your environment, not by Anthropic.

1010 supportedModels:

11 - claude-fable-5-2

12 - claude-mythos-5-2

1113 - claude-fable-5-1

1214 - claude-mythos-5-1

1315 - claude-fable-5

from line 35

3335 Claude Models on Google Cloud (Google managed): stable

3436 Microsoft Foundry: stable

3537 details:

36 - Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 support computer use through the `computer_toolset_20260801` toolset. They return a 400 error for any computer use tool version they don't accept, such as `computer_20251124` on the Claude API. To move a `computer_20251124` integration to the toolset, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). To move from `computer_20250124`, see [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset) in the Claude Haiku 5.5 migration guide.

38 - Claude Fable 5.2, Claude Mythos 5.2, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 support computer use through the `computer_toolset_20260801` toolset. They return a 400 error for any computer use tool version they don't accept, such as `computer_20251124` on the Claude API. To move a `computer_20251124` integration to the toolset, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). To move from `computer_20250124`, see [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset) in the Claude Haiku 5.5 migration guide.

3739 - Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 4.6, and Claude Opus 4.5 support computer use only through the `computer_20251124` tool version, which requires a beta header; see [Earlier tool versions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#earlier-tool-versions).

3840---

3941

from line 1830

18281830

18291831* Place one `cache_control` breakpoint after the system prompt and tool definitions, and up to three more on the last `tool_result` block of each of the most recent turns, advancing them each turn. Within a [batch action](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#batch-actions), markers on several blocks act as a single breakpoint, but each still counts toward the limit of four, so use at most one in any turn.

18301832* Prune old screenshots in *batches*, not one each turn. Dropping a screenshot every turn changes the prefix every turn and invalidates the cache. A reasonable default is to keep the last three screenshots and prune every 25 turns, so the prefix stays byte-identical between prune events; if your screenshots exceed the stricter limit, choose an interval that keeps each request at 20 or fewer images.

1831* On Claude 5.1 and later models, avoid pruning on the client: removing an earlier screenshot from a request [invalidates every later thinking block](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-in-conversation) in that request and in every later request. Resize screenshots to stay under the stricter limit instead and use server-side [tool result clearing](https://platform.claude.com/docs/en/build-with-claude/context-editing#tool-result-clearing) to drop old ones from the context. If you must prune, keep [`prefix_mismatch_behavior: "drop_block"`](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-thinking-controls) set from then on; after each prune, Claude continues without the thinking produced since the pruned screenshot, on that request and every later one. On Claude Sonnet 5.5 and Claude Haiku 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`. With any other thinking setting on those models, keep the history append-only or strip every `thinking` and `redacted_thinking` block after the pruned screenshot.

1833* On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5, avoid pruning on the client: removing an earlier screenshot from a request [invalidates every later thinking block](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-in-conversation) in that request and in every later request. Resize screenshots to stay under the stricter limit instead and use server-side [tool result clearing](https://platform.claude.com/docs/en/build-with-claude/context-editing#tool-result-clearing) to drop old ones from the context. If you must prune, keep [`prefix_mismatch_behavior: "drop_block"`](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-thinking-controls) set from then on; after each prune, Claude continues without the thinking produced since the pruned screenshot, on that request and every later one. On Claude Sonnet 5.5 and Claude Haiku 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`. With any other thinking setting on those models, keep the history append-only or strip every `thinking` and `redacted_thinking` block after the pruned screenshot.

18321834

18331835### Diagnose click issues

18341836

from line 2265

22632265

22642266* Availability: Available

22652267

2266| Status | Cloud platforms | Models |

2267| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2268| Available | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

2269| Available | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

2270| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Amazon Bedrock (InvokeModel)](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview), [Claude Sonnet 4.5](https://platform.claude.com/docs/en/models/sonnet-4-5/overview) |

2268| Status | Cloud platforms | Models |

2269| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

2270| Available | Claude API, [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

2271| Available | [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

2272| Available | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview) |

2273| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Amazon Bedrock (InvokeModel)](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Haiku 4.5](https://platform.claude.com/docs/en/models/haiku-4-5/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview), [Claude Sonnet 4.5](https://platform.claude.com/docs/en/models/sonnet-4-5/overview) |

22712274

22722275#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

22732276

agents-and-tools/tool-use/define-tools Changed · +6 / -4 lines

from line 5

55featureMetadata:

66 status: stable

77 supportedModels:

8 - claude-fable-5-2

9 - claude-mythos-5-2

810 - claude-fable-5-1

911 - claude-mythos-5-1

1012 - claude-fable-5

from line 589

587589

588590Not every model and setting supports forced tool use. Where it isn’t supported, `tool_choice: {"type": "any"}` and `tool_choice: {"type": "tool", "name": "..."}` fail, whereas `tool_choice: {"type": "auto"}` (the default) and `tool_choice: {"type": "none"}` still work:

589591

590| Model or setting | Restriction | What to use instead |

591| --------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

592| Manual [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) (`thinking: {type: "enabled"}`) | `any` and `tool` are not supported and result in an error | `auto` or `none`. [Adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) itself doesn’t block forced tool use (models with thinking on by default, such as Claude Opus 5 and Claude Haiku 5.5, accept it, but a forced call skips thinking: the response starts with the tool call and has no `thinking` block); the models in the next row reject forced tool use regardless of thinking settings |

593| Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) | `any` and `tool` return a [400 error](https://platform.claude.com/docs/en/api/errors#forced-tool-use-not-supported) | `auto` with [strict tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/strict-tool-use) to guarantee schema-valid tool inputs, or [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs) when you need a response in a fixed JSON shape. Prompting still influences which tool `auto` picks. `none` is also supported |

592| Model or setting | Restriction | What to use instead |

593| ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

594| Manual [extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking) (`thinking: {type: "enabled"}`) | `any` and `tool` are not supported and result in an error | `auto` or `none`. [Adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) itself doesn’t block forced tool use (models with thinking on by default, such as Claude Opus 5 and Claude Haiku 5.5, accept it, but a forced call skips thinking: the response starts with the tool call and has no `thinking` block); the models in the next row reject forced tool use regardless of thinking settings |

595| Claude Fable 5.2, [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) | `any` and `tool` return a [400 error](https://platform.claude.com/docs/en/api/errors#forced-tool-use-not-supported) | `auto` with [strict tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/strict-tool-use) to guarantee schema-valid tool inputs, or [structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs) when you need a response in a fixed JSON shape. Prompting still influences which tool `auto` picks. `none` is also supported |

594596

595597On models that support it, the highlighted lines are the only difference from a standard tool use request:

596598

agents-and-tools/tool-use/programmatic-tool-calling Changed · +5 / -3 lines

from line 8

88 eligibility: not-eligible

99 note: Built on code execution containers; data retained up to 30 days.

1010 supportedModels:

11 - claude-fable-5-2

12 - claude-mythos-5-2

1113 - claude-fable-5-1

1214 - claude-mythos-5-1

1315 - claude-fable-5

from line 1587

15851587

15861588* Availability: Available

15871589

1588| Status | Cloud platforms | Models |

1589| --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1590| Available | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Microsoft Foundry (hosted on Anthropic)](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview), [Claude Sonnet 4.5](https://platform.claude.com/docs/en/models/sonnet-4-5/overview) |

1590| Status | Cloud platforms | Models |

1591| --------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

1592| Available | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Microsoft Foundry (hosted on Anthropic)](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview), [Claude Sonnet 4.5](https://platform.claude.com/docs/en/models/sonnet-4-5/overview) |

15911593

15921594#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

15931595

api/errors Changed · +5 / -5 lines

from line 476

476476

477477### Thinking cannot be disabled

478478

479On Claude Fable 5.1, [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), Claude Fable 5, [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Opus 5.5, and [Claude Mythos Preview](https://anthropic.com/glasswing), thinking is always on. Sending `thinking: {"type": "disabled"}` to any of these models returns a 400 `invalid_request_error`. On all of these models except Claude Mythos Preview, the message reads:

479On Claude Fable 5.2, [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), Claude Fable 5.1, [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), Claude Fable 5, [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Opus 5.5, and [Claude Mythos Preview](https://anthropic.com/glasswing), thinking is always on. Sending `thinking: {"type": "disabled"}` to any of these models returns a 400 `invalid_request_error`. On all of these models except Claude Mythos Preview, the message reads:

480480

481481```text wrap

482482"thinking.type.disabled" is not supported for this model. Use "thinking.type.adaptive" and "output_config.effort" to control thinking behavior.

from line 522

522522

523523### Forced tool use not supported

524524

525Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) don’t support forced tool use. Sending `tool_choice: {"type": "any"}` or `tool_choice: {"type": "tool", "name": "..."}` to any of these models, including on the [token counting endpoint](https://platform.claude.com/docs/en/build-with-claude/token-counting), returns a 400 `invalid_request_error`:

525Claude Fable 5.2, [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), Claude Opus 5.5, Claude Sonnet 5.5, Claude Fable 5.1, and [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview) don’t support forced tool use. Sending `tool_choice: {"type": "any"}` or `tool_choice: {"type": "tool", "name": "..."}` to any of these models, including on the [token counting endpoint](https://platform.claude.com/docs/en/build-with-claude/token-counting), returns a 400 `invalid_request_error`:

526526

527527```text wrap

528528tool_choice: type "tool" and "any" are not supported for this model.

from line 532

532532

533533### Computer use tool version not supported

534534

535Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 return a 400 error for any [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) tool version they don’t accept. On the Claude API, that includes `computer_20251124` with its beta header. They don’t accept `computer_20250124` on any platform. The Claude API’s `invalid_request_error` message names the rejected type and, after `Did you mean one of`, lists the tool types the model accepts. For Claude Opus 5.5, the message begins:

535Claude Fable 5.2, Claude Mythos 5.2, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 return a 400 error for any [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) tool version they don’t accept. On the Claude API, that includes `computer_20251124` with its beta header. They don’t accept `computer_20250124` on any platform. The Claude API’s `invalid_request_error` message names the rejected type and, after `Did you mean one of`, lists the tool types the model accepts. For Claude Opus 5.5, the message begins:

536536

537537```text wrap

538538'claude-opus-5-5' does not support tool types: computer_20251124.

539539```

540540

541The Claude API returns the same message for any Anthropic-defined tool type that the requested model doesn’t support. Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 support computer use through the `computer_toolset_20260801` toolset. Declare `{"type": "computer_toolset_20260801"}` without the beta header and update your agent loop as described in [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). To move from `computer_20250124`, see [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset) in the Claude Haiku 5.5 migration guide.

541The Claude API returns the same message for any Anthropic-defined tool type that the requested model doesn’t support. Claude Fable 5.2, Claude Mythos 5.2, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 support computer use through the `computer_toolset_20260801` toolset. Declare `{"type": "computer_toolset_20260801"}` without the beta header and update your agent loop as described in [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). To move from `computer_20250124`, see [Move computer use to the toolset](https://platform.claude.com/docs/en/models/haiku-5-5/migration-guide#computer-use-toolset) in the Claude Haiku 5.5 migration guide.

542542

543543On Amazon Bedrock, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 also accept the `computer_20251124` tool with the `computer-use-2025-11-24` beta header. [Earlier tool versions](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#earlier-tool-versions) lists the models to use with each earlier version.

544544

545545### Thinking block bound to a different conversation

546546

547This 400 `invalid_request_error` usually means a thinking block you sent back failed the prefix check: something before the block changed after the block was produced, such as the `system` prompt, `tools`, or an earlier message. Claude 5.1 and later models run this check. For requests that don’t set `prefix_mismatch_behavior`, [When `prefix_mismatch_behavior` is unset](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#enforcement) shows which ones get this error. The message starts with the position of the first failing block:

547This 400 `invalid_request_error` usually means a thinking block you sent back failed the prefix check: something before the block changed after the block was produced, such as the `system` prompt, `tools`, or an earlier message. Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5 run this check. For requests that don’t set `prefix_mismatch_behavior`, [When `prefix_mismatch_behavior` is unset](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking#enforcement) shows which ones get this error. The message starts with the position of the first failing block:

548548

549549```text wrap

550550messages.{i}.content.{j}: Invalid `signature` in `thinking` block. The block is bound to a different conversation. Remove the block, or set `thinking.block_binding.prefix_mismatch_behavior` to "drop_block".

api/rate-limits Changed · +38 / -35 lines

from line 130

130130

131131<Tabs>

132132 <Tab title="Start tier">

134 | ----------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

135 | Claude Fable 5.x1 | 4,000 | 500,000 | 100,000 |

136 | Claude Opus 5.5 | 4,000 | 2,000,000 | 400,000 |

137 | Claude Opus 5 | 1,000 | 2,000,000 | 400,000 |

138 | Claude Opus 4.x2 | 1,000 | 2,000,000 | 400,000 |

139 | Claude Sonnet 5.5 | 4,000 | 2,000,000 | 400,000 |

140 | Claude Sonnet 5 | 1,000 | 2,000,000 | 400,000 |

141 | Claude Sonnet 4.x3 | 1,000 | 2,000,000 | 400,000 |

142 | Claude Haiku 5.5 | 4,000 | 2,000,000 | 400,000 |

143 | Claude Haiku 4.5 | 1,000 | 2,000,000 | 400,000 |

134 | ----------------------------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

135 | Claude Fable 5.2 | 4,000 | 500,000 | 100,000 |

136 | Claude Fable 5.1 and Claude Fable 51 | 4,000 | 500,000 | 100,000 |

137 | Claude Opus 5.5 | 4,000 | 2,000,000 | 400,000 |

138 | Claude Opus 5 | 1,000 | 2,000,000 | 400,000 |

139 | Claude Opus 4.x2 | 1,000 | 2,000,000 | 400,000 |

140 | Claude Sonnet 5.5 | 4,000 | 2,000,000 | 400,000 |

141 | Claude Sonnet 5 | 1,000 | 2,000,000 | 400,000 |

142 | Claude Sonnet 4.x3 | 1,000 | 2,000,000 | 400,000 |

143 | Claude Haiku 5.5 | 4,000 | 2,000,000 | 400,000 |

144 | Claude Haiku 4.5 | 1,000 | 2,000,000 | 400,000 |

144145 </Tab>

145146

146147 <Tab title="Build tier">

148 | ----------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

149 | Claude Fable 5.x1 | 10,000 | 1,500,000 | 300,000 |

150 | Claude Opus 5.5 | 10,000 | 5,000,000 | 1,000,000 |

151 | Claude Opus 5 | 5,000 | 5,000,000 | 1,000,000 |

152 | Claude Opus 4.x2 | 5,000 | 5,000,000 | 1,000,000 |

153 | Claude Sonnet 5.5 | 10,000 | 5,000,000 | 1,000,000 |

154 | Claude Sonnet 5 | 5,000 | 5,000,000 | 1,000,000 |

155 | Claude Sonnet 4.x3 | 5,000 | 5,000,000 | 1,000,000 |

156 | Claude Haiku 5.5 | 10,000 | 5,000,000 | 1,000,000 |

157 | Claude Haiku 4.5 | 5,000 | 5,000,000 | 1,000,000 |

149 | ----------------------------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

150 | Claude Fable 5.2 | 10,000 | 1,500,000 | 300,000 |

151 | Claude Fable 5.1 and Claude Fable 51 | 10,000 | 1,500,000 | 300,000 |

152 | Claude Opus 5.5 | 10,000 | 5,000,000 | 1,000,000 |

153 | Claude Opus 5 | 5,000 | 5,000,000 | 1,000,000 |

154 | Claude Opus 4.x2 | 5,000 | 5,000,000 | 1,000,000 |

155 | Claude Sonnet 5.5 | 10,000 | 5,000,000 | 1,000,000 |

156 | Claude Sonnet 5 | 5,000 | 5,000,000 | 1,000,000 |

157 | Claude Sonnet 4.x3 | 5,000 | 5,000,000 | 1,000,000 |

158 | Claude Haiku 5.5 | 10,000 | 5,000,000 | 1,000,000 |

159 | Claude Haiku 4.5 | 5,000 | 5,000,000 | 1,000,000 |

158160 </Tab>

159161

160162 <Tab title="Scale tier">

162 | ----------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

163 | Claude Fable 5.x1 | 13,000 | 4,000,000 | 800,000 |

164 | Claude Opus 5.5 | 13,000 | 10,000,000 | 2,000,000 |

165 | Claude Opus 5 | 10,000 | 10,000,000 | 2,000,000 |

166 | Claude Opus 4.x2 | 10,000 | 10,000,000 | 2,000,000 |

167 | Claude Sonnet 5.5 | 13,000 | 10,000,000 | 2,000,000 |

168 | Claude Sonnet 5 | 10,000 | 10,000,000 | 2,000,000 |

169 | Claude Sonnet 4.x3 | 10,000 | 10,000,000 | 2,000,000 |

170 | Claude Haiku 5.5 | 13,000 | 10,000,000 | 2,000,000 |

171 | Claude Haiku 4.5 | 10,000 | 10,000,000 | 2,000,000 |

164 | ----------------------------------------------- | --------------------------------- | -------------------------------------- | --------------------------------------- |

165 | Claude Fable 5.2 | 13,000 | 4,000,000 | 800,000 |

166 | Claude Fable 5.1 and Claude Fable 51 | 13,000 | 4,000,000 | 800,000 |

167 | Claude Opus 5.5 | 13,000 | 10,000,000 | 2,000,000 |

168 | Claude Opus 5 | 10,000 | 10,000,000 | 2,000,000 |

169 | Claude Opus 4.x2 | 10,000 | 10,000,000 | 2,000,000 |

170 | Claude Sonnet 5.5 | 13,000 | 10,000,000 | 2,000,000 |

171 | Claude Sonnet 5 | 10,000 | 10,000,000 | 2,000,000 |

172 | Claude Sonnet 4.x3 | 10,000 | 10,000,000 | 2,000,000 |

173 | Claude Haiku 5.5 | 13,000 | 10,000,000 | 2,000,000 |

174 | Claude Haiku 4.5 | 10,000 | 10,000,000 | 2,000,000 |

172175 </Tab>

173176

174177 <Tab title="Custom tier">

from line 179

176179 </Tab>

177180</Tabs>

178181

179*1 Fable rate limit is a total limit that applies to combined traffic across Claude Fable 5.1 and Claude Fable 5. Claude Mythos 5.1 and Claude Mythos 5 share a separate combined limit.*

182*1 Fable rate limit is a total limit that applies to combined traffic across Claude Fable 5.1 and Claude Fable 5. Claude Fable 5.2 has a separate rate limit and is not part of this combined bucket. Claude Mythos 5.2, Claude Mythos 5.1, and Claude Mythos 5 share a separate combined limit.*

180183

181184*2 Opus rate limit is a total limit that applies to combined traffic across Claude Opus 4.8, Opus 4.7, Opus 4.6, and Opus 4.5. Claude Opus 5.5 and Claude Opus 5 each have a separate rate limit and are not part of this combined bucket.*

182185

from line 228

225228

226229### Fast mode rate limits

227230

228When you use [fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) with `speed: "fast"` on Claude Opus 5.5, Claude Opus 5, or Claude Opus 4.8, dedicated rate limits apply. They are separate from standard rate limits. Claude Opus 5.5 has a default fast mode rate limit in the Start, Build, and Scale tiers, so you don’t need to request access to use fast mode with it. Organizations in the Evaluation tier can use fast mode with Claude Opus 5.5 once they move to the Start, Build, or Scale tier. Fast mode for Claude Opus 5 and Claude Opus 4.8 is in research preview. To see your fast mode rate limits, go to the [Rate limits](https://platform.claude.com/usage/limits) page in the Claude Console. When you exceed your fast mode rate limits, the API returns a `429` error with a `retry-after` header.

231When you use [fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) with `speed: "fast"` on Claude Fable 5.2, Claude Mythos 5.2, Claude Opus 5.5, Claude Opus 5, or Claude Opus 4.8, dedicated rate limits apply. They are separate from standard rate limits. Claude Opus 5.5 has a default fast mode rate limit in the Start, Build, and Scale tiers, so you don’t need to request access to use fast mode with it. Organizations in the Evaluation tier can use fast mode with Claude Opus 5.5 once they move to the Start, Build, or Scale tier. The same applies to Claude Fable 5.2. It also applies to Claude Mythos 5.2. Fast mode for Claude Opus 5 and Claude Opus 4.8 is in research preview. To see your fast mode rate limits, go to the [Rate limits](https://platform.claude.com/usage/limits) page in the Claude Console. When you exceed your fast mode rate limits, the API returns a `429` error with a `retry-after` header.

229232

230233The response includes `anthropic-fast-*` headers that indicate your fast mode rate limit status. See [Fast mode rate limits](https://platform.claude.com/docs/en/build-with-claude/fast-mode#rate-limits) for details on these headers.

231234

build-with-claude/claude-in-amazon-bedrock Changed · +4 / -4 lines

from line 100

100100 <Tabs>

101101 <Tab title="Gradle">

102102 ```kotlin

103 implementation("com.anthropic:anthropic-java:3.6.0")

104 implementation("com.anthropic:anthropic-java-bedrock:3.6.0")

103 implementation("com.anthropic:anthropic-java:3.7.0")

104 implementation("com.anthropic:anthropic-java-bedrock:3.7.0")

105105 ```

106106 </Tab>

107107

from line 110

110110 <dependency>

111111 <groupId>com.anthropic</groupId>

112112 <artifactId>anthropic-java</artifactId>

113 <version>3.6.0</version>

113 <version>3.7.0</version>

114114 </dependency>

115115 <dependency>

116116 <groupId>com.anthropic</groupId>

117117 <artifactId>anthropic-java-bedrock</artifactId>

118 <version>3.6.0</version>

118 <version>3.7.0</version>

119119 </dependency>

120120 ```

121121 </Tab>

build-with-claude/claude-in-microsoft-foundry Changed · +4 / -4 lines

from line 76

7676 <Tabs>

7777 <Tab title="Gradle">

7878 ```kotlin

79 implementation("com.anthropic:anthropic-java:3.6.0")

80 implementation("com.anthropic:anthropic-java-foundry:3.6.0")

79 implementation("com.anthropic:anthropic-java:3.7.0")

80 implementation("com.anthropic:anthropic-java-foundry:3.7.0")

8181 ```

8282 </Tab>

8383

from line 86

8686 <dependency>

8787 <groupId>com.anthropic</groupId>

8888 <artifactId>anthropic-java</artifactId>

89 <version>3.6.0</version>

89 <version>3.7.0</version>

9090 </dependency>

9191 <dependency>

9292 <groupId>com.anthropic</groupId>

9393 <artifactId>anthropic-java-foundry</artifactId>

94 <version>3.6.0</version>

94 <version>3.7.0</version>

9595 </dependency>

9696 ```

9797 </Tab>

build-with-claude/claude-models-on-google-cloud/anthropic-managed Changed · +5 / -5 lines

from line 177

177177 <Tabs>

178178 <Tab title="Gradle">

179179 ```kotlin

180 implementation("com.anthropic:anthropic-java:3.6.0")

181 implementation("com.anthropic:anthropic-java-google-cloud:3.6.0")

180 implementation("com.anthropic:anthropic-java:3.7.0")

181 implementation("com.anthropic:anthropic-java-google-cloud:3.7.0")

182182 ```

183183 </Tab>

184184

from line 187

187187 <dependency>

188188 <groupId>com.anthropic</groupId>

189189 <artifactId>anthropic-java</artifactId>

190 <version>3.6.0</version>

190 <version>3.7.0</version>

191191 </dependency>

192192 <dependency>

193193 <groupId>com.anthropic</groupId>

194194 <artifactId>anthropic-java-google-cloud</artifactId>

195 <version>3.6.0</version>

195 <version>3.7.0</version>

196196 </dependency>

197197 ```

198198 </Tab>

from line 544

544544* [Thinking](https://platform.claude.com/docs/en/build-with-claude/thinking)

545545 * [Adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking-steering-and-cost)

546546 * [Extended thinking](https://platform.claude.com/docs/en/build-with-claude/extended-thinking)

547 * [Preserved thinking](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking)

547548* [Token counting](https://platform.claude.com/docs/en/build-with-claude/token-counting)

548549* [Tool runner](https://platform.claude.com/docs/en/agents-and-tools/tool-use/tool-runner) (Beta)

549550* [Vision (images)](https://platform.claude.com/docs/en/build-with-claude/vision)

from line 571

570571 * [Session threads](https://platform.claude.com/docs/en/managed-agents/session-threads) (Beta)

571572* [Outcomes](https://platform.claude.com/docs/en/managed-agents/define-outcomes) (Beta)

572573* [Permission policies](https://platform.claude.com/docs/en/managed-agents/permission-policies) (Beta)

573* [Preserved thinking](https://platform.claude.com/docs/en/build-with-claude/preserved-thinking)

574574* [Scheduled deployments](https://platform.claude.com/docs/en/managed-agents/scheduled-deployments) (Beta)

575575* [Self-hosted sandboxes](https://platform.claude.com/docs/en/managed-agents/self-hosted-sandboxes) (Beta)

576576* [Session budgets](https://platform.claude.com/docs/en/managed-agents/budgets) (Beta)

build-with-claude/claude-models-on-google-cloud/google-managed Changed · +10 / -4 lines

from line 49

4949 <Tabs>

5050 <Tab title="Gradle">

5151 ```kotlin

52 implementation("com.anthropic:anthropic-java:3.6.0")

53 implementation("com.anthropic:anthropic-java-vertex:3.6.0")

52 implementation("com.anthropic:anthropic-java:3.7.0")

53 implementation("com.anthropic:anthropic-java-vertex:3.7.0")

5454 ```

5555 </Tab>

5656

from line 59

5959 <dependency>

6060 <groupId>com.anthropic</groupId>

6161 <artifactId>anthropic-java</artifactId>

62 <version>3.6.0</version>

62 <version>3.7.0</version>

6363 </dependency>

6464 <dependency>

6565 <groupId>com.anthropic</groupId>

6666 <artifactId>anthropic-java-vertex</artifactId>

67 <version>3.6.0</version>

67 <version>3.7.0</version>

6868 </dependency>

6969 ```

7070 </Tab>

from line 289

289289

290290| Model | Agent Platform API model ID |

291291| :---------------------------------------------------------------------------------------------------- | :--------------------------- |

292| Claude Fable 5.2 | `claude-fable-5-2` |

293| Claude Mythos 5.2 ([limited availability](https://support.claude.com/en/articles/14604842)) | `claude-mythos-5-2` |

292294| Claude Fable 5.1 | `claude-fable-5-1` |

293295| Claude Mythos 5.1 ([limited availability](https://support.claude.com/en/articles/14604842)) | `claude-mythos-5-1` |

294296| Claude Fable 5 | `claude-fable-5` |

from line 474

472474

473475* [Structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

474476

477* [Fast mode](https://platform.claude.com/docs/en/build-with-claude/fast-mode) on [supported models](https://platform.claude.com/docs/en/build-with-claude/fast-mode#feature-availability)

478

475479[Features overview](https://platform.claude.com/docs/en/build-with-claude/overview) lists every feature. Each feature’s page shows whether Claude Models on Google Cloud (Google managed) supports it.

476480

477481### Features not supported

from line 495

491495

492496Claude Models on Google Cloud (Google managed) offers a [1M-token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows) for these models:

493497

498* Claude Fable 5.2

499* Claude Mythos 5.2

494500* Claude Fable 5.1

495501* Claude Mythos 5.1

496502* Claude Fable 5

build-with-claude/claude-platform-on-aws Changed · +5 / -4 lines

from line 313

313313 <Tabs>

314314 <Tab title="Gradle">

315315 ```kotlin

316 implementation("com.anthropic:anthropic-java:3.6.0")

317 implementation("com.anthropic:anthropic-java-aws:3.6.0")

316 implementation("com.anthropic:anthropic-java:3.7.0")

317 implementation("com.anthropic:anthropic-java-aws:3.7.0")

318318 ```

319319 </Tab>

320320

from line 323

323323 <dependency>

324324 <groupId>com.anthropic</groupId>

325325 <artifactId>anthropic-java</artifactId>

326 <version>3.6.0</version>

326 <version>3.7.0</version>

327327 </dependency>

328328 <dependency>

329329 <groupId>com.anthropic</groupId>

330330 <artifactId>anthropic-java-aws</artifactId>

331 <version>3.6.0</version>

331 <version>3.7.0</version>

332332 </dependency>

333333 ```

334334 </Tab>

from line 358

358358

359359| Model | Model ID |

360360| :---------------------------------------------------------------------------------------------------- | :------------------ |

361| Claude Fable 5.2 | `claude-fable-5-2` |

361362| Claude Fable 5.1 | `claude-fable-5-1` |

362363| Claude Fable 5 | `claude-fable-5` |

363364| Claude Opus 5.5 | `claude-opus-5-5` |

build-with-claude/compaction-background Changed · +6 / -4 lines

from line 6

66 status: beta

77 betaHeader: compact-2026-09-04

88 supportedModels:

9 - claude-fable-5-2

10 - claude-mythos-5-2

911 - claude-fable-5-1

1012 - claude-mythos-5-1

1113 - claude-fable-5

from line 559

557559

558560* Availability: Available

559561

560| Status | Cloud platforms | Models |

561| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

562| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

563| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

562| Status | Cloud platforms | Models |

563| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

564| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

565| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

564566

565567### Required beta headers

566568

build-with-claude/compaction-keep-recent-turns Changed · +6 / -4 lines

from line 6

66 status: beta

77 betaHeader: compact-2026-09-04

88 supportedModels:

9 - claude-fable-5-2

10 - claude-mythos-5-2

911 - claude-fable-5-1

1012 - claude-mythos-5-1

1113 - claude-fable-5

from line 514

512514

513515* Availability: Available

514516

515| Status | Cloud platforms | Models |

516| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

517| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

518| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

517| Status | Cloud platforms | Models |

518| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

519| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

520| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

519521

520522### Required beta headers

521523

build-with-claude/compaction-on-demand Changed · +6 / -4 lines

from line 6

66 status: beta

77 betaHeader: compact-2026-09-04

88 supportedModels:

9 - claude-fable-5-2

10 - claude-mythos-5-2

911 - claude-fable-5-1

1012 - claude-mythos-5-1

1113 - claude-fable-5

from line 842

840842

841843* Availability: Available

842844

843| Status | Cloud platforms | Models |

844| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

845| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

846| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

845| Status | Cloud platforms | Models |

846| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

847| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

848| Beta | [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview) |

847849

848850### Required beta headers

849851

build-with-claude/compaction-thinking-blocks Changed · +5 / -3 lines

from line 6

66 status: beta

77 betaHeader: compact-2026-09-04

88 supportedModels:

9 - claude-fable-5-2

10 - claude-mythos-5-2

911 - claude-fable-5-1

1012 - claude-mythos-5-1

1113 - claude-fable-5

from line 704

702704

703705* Availability: Available

704706

705| Status | Cloud platforms | Models |

706| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

707| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

707| Status | Cloud platforms | Models |

708| ------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

709| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

708710

709711### Required beta headers

710712

build-with-claude/compaction-threshold Changed · +11 / -9 lines

from line 9

99 eligibility: eligible

1010 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements). Server-side compaction results are returned and round-tripped statelessly through the API response.

1111 supportedModels:

12 - claude-fable-5-2

13 - claude-mythos-5-2

1214 - claude-fable-5-1

1315 - claude-mythos-5-1

1416 - claude-fable-5

from line 734

732734 ```

733735</CodeGroup>

734736

735On Claude 5.1 and later models, a request with custom `instructions` summarizes from the visible conversation only: earlier thinking blocks are not part of the summarizer’s input.

737On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5, a request with custom `instructions` summarizes from the visible conversation only: earlier thinking blocks are not part of the summarizer’s input.

736738

737739### Pausing after compaction

738740

from line 1662

16601662

16611663If no summary is generated, the block’s `content` is `null` and the API ignores the block. Nothing is compacted, so keep the original messages.

16621664

1663On Claude 5.1 and later models, thinking blocks from before a `compaction` block aren’t carried forward, so the summary is all the model has of that earlier work. If you write your own `instructions`, tell the model what the summary must retain; see [Tell the model what to preserve in compaction summaries](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1#tell-the-model-what-to-preserve-in-compaction-summaries).

1665Thinking blocks from before a `compaction` block aren’t carried forward, so the summary is all the model has of that earlier work. If you write your own `instructions`, tell the model what the summary must retain; see [Tell the model what to preserve in compaction summaries](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1#tell-the-model-what-to-preserve-in-compaction-summaries).

16641666

16651667### Streaming

16661668

from line 2777

27752777 ```

27762778</CodeGroup>

27772779

2778On Claude 5.1 and later models, thinking blocks in any assistant turn you reinsert after the compaction block fail the [prefix check](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-in-conversation), because they were produced when the full history was present. Strip the `thinking` and `redacted_thinking` blocks from those turns. Alternatively, send `thinking.block_binding.prefix_mismatch_behavior: "drop_block"` with the `thinking-binding-controls-2026-08-01` [beta header](https://platform.claude.com/docs/en/api/beta-headers). The preserved text and tool blocks can stay as they are. Letting the API summarize everything, without reinserting earlier turns, avoids this. On Claude Sonnet 5.5 and Claude Haiku 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`. With any other thinking setting on those models, strip the blocks.

2780On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Sonnet 5.5, and Claude Haiku 5.5, thinking blocks in any assistant turn you reinsert after the compaction block fail the [prefix check](https://platform.claude.com/docs/en/build-with-claude/thinking#preserved-in-conversation), because they were produced when the full history was present. Strip the `thinking` and `redacted_thinking` blocks from those turns. Alternatively, send `thinking.block_binding.prefix_mismatch_behavior: "drop_block"` with the `thinking-binding-controls-2026-08-01` [beta header](https://platform.claude.com/docs/en/api/beta-headers). The preserved text and tool blocks can stay as they are. Letting the API summarize everything, without reinserting earlier turns, avoids this. On Claude Sonnet 5.5 and Claude Haiku 5.5, `block_binding` works only with `thinking: {"type": "adaptive"}`. With any other thinking setting on those models, strip the blocks.

27792781

27802782Here’s an example that uses `pause_after_compaction` to preserve the prior exchange and the current user message (three messages total) instead of summarizing them. It keeps their text and tool blocks unchanged, removes the `thinking` and `redacted_thinking` blocks from the preserved assistant turn, and drops that turn if nothing else is left:

27812783

from line 3456

34543456* Availability: Available

34553457* Usage: Opt in with a `compact_20260112` edit in `context_management.edits`. Compaction starts when input tokens reach the trigger, 150,000 by default and at least 50,000.

34563458

3457| Status | Cloud platforms | Models |

3458| ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

3459| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Amazon Bedrock (InvokeModel)](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

3459| Status | Cloud platforms | Models |

3460| ------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

3461| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Amazon Bedrock (InvokeModel)](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

34603462

34613463#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

34623464

from line 3465

34633465* Availability: Always on

34643466* Usage: It compacts the session’s conversation history to fit the context window, and each compaction emits an `agent.thread_context_compacted` event.

34653467

3466| Status | Cloud platforms | Models |

3467| ------ | ------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

3468| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

3468| Status | Cloud platforms | Models |

3469| ------ | ------------------------------------------------------------------------------------------------------------------ | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

3470| Beta | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview) |

34693471

34703472### Required beta headers

34713473

build-with-claude/context-windows Changed · +3 / -3 lines

from line 35

3535

3636## Context window sizes by model

3737

38Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 5.5, Claude Sonnet 5, Claude Sonnet 4.6, Claude Haiku 5.5, and [Claude Mythos Preview](https://anthropic.com/glasswing) have a 1M-token context window. A single request to any of them can generate up to 128k output tokens (`max_tokens`). Other Claude models, including Claude Sonnet 4.5 (deprecated), have a 200k-token context window.

38Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 5.5, Claude Sonnet 5, Claude Sonnet 4.6, Claude Haiku 5.5, and [Claude Mythos Preview](https://anthropic.com/glasswing) have a 1M-token context window. A single request to any of them can generate up to 128k output tokens (`max_tokens`). Other Claude models, including Claude Sonnet 4.5 (deprecated), have a 200k-token context window.

3939

4040For every model with a 1M-token context window, 1M is the default: you don’t need a beta header, and long-context requests are billed at [standard pricing](https://platform.claude.com/docs/en/about-claude/pricing#long-context-pricing), except on Claude Haiku 5.5, where prompts over 100,000 tokens cost more.

4141

from line 49

4949

5050Thinking tokens are a subset of your `max_tokens` parameter, are billed as output tokens, and count toward rate limits. With [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking), Claude determines its thinking allocation dynamically, so thinking token usage varies from request to request.

5151

52Whether thinking blocks from previous assistant turns stay in the context window depends on the model. On Claude Opus 4.5 and later Opus models, Claude Sonnet 4.6 and later Sonnet models, Claude Haiku 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, and Claude Mythos Preview, the API keeps previous thinking blocks by default, and they count toward the context window like any other input tokens. On earlier Opus and Sonnet models and all Haiku models through Claude Haiku 4.5, the API automatically strips previous thinking blocks from the conversation history when you pass them back, which preserves token capacity for conversation content. For the per-model defaults, see [thinking block preservation by model](https://platform.claude.com/docs/en/build-with-claude/thinking#thinking-block-preservation-by-model). To override the default in either direction, use [thinking block clearing](https://platform.claude.com/docs/en/build-with-claude/context-editing#thinking-block-clearing).

52Whether thinking blocks from previous assistant turns stay in the context window depends on the model. On Claude Opus 4.5 and later Opus models, Claude Sonnet 4.6 and later Sonnet models, Claude Haiku 5.5, Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, and Claude Mythos Preview, the API keeps previous thinking blocks by default, and they count toward the context window like any other input tokens. On earlier Opus and Sonnet models and all Haiku models through Claude Haiku 4.5, the API automatically strips previous thinking blocks from the conversation history when you pass them back, which preserves token capacity for conversation content. For the per-model defaults, see [thinking block preservation by model](https://platform.claude.com/docs/en/build-with-claude/thinking#thinking-block-preservation-by-model). To override the default in either direction, use [thinking block clearing](https://platform.claude.com/docs/en/build-with-claude/context-editing#thinking-block-clearing).

5353

5454The following diagram shows how tokens are managed when thinking is enabled on a model that strips previous thinking blocks:

5555

from line 127

127127

128128Image tokens are included in these budgets.

129129

130Claude Opus 4.7 and later Opus models, Claude Sonnet 5.5, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, and Claude Haiku 5.5 don’t receive these injected tags. On these models, you can give the model an explicit budget with [task budgets](https://platform.claude.com/docs/en/build-with-claude/task-budgets), which are in beta.

130Claude Opus 4.7 and later Opus models, Claude Sonnet 5.5, Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, and Claude Haiku 5.5 don’t receive these injected tags. On these models, you can give the model an explicit budget with [task budgets](https://platform.claude.com/docs/en/build-with-claude/task-budgets), which are in beta.

131131

132132<Tip>

133133 For agents that span multiple sessions, design your state artifacts so that context recovery is fast when a new session starts. The [memory tool’s multisession pattern](https://platform.claude.com/docs/en/agents-and-tools/tool-use/memory-tool#multisession-software-development-pattern) walks through a concrete approach. See also [Effective harnesses for long-running agents](https://www.anthropic.com/engineering/effective-harnesses-for-long-running-agents).

build-with-claude/effort Changed · +52 / -42 lines

from line 8

88 eligibility: eligible

99 note: Excludes [Covered Models](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention#model-specific-data-retention-requirements).

1010 supportedModels:

11 - claude-fable-5-2

12 - claude-mythos-5-2

1113 - claude-fable-5-1

1214 - claude-mythos-5-1

1315 - claude-fable-5

from line 243

241243

242244### Effort levels

243245

244| Level | Description | Typical use case |

245| -------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |

246| `max` | Absolute maximum capability with no constraints on token spending. Available on Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Mythos Preview, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 5.5, Claude Sonnet 5, Claude Sonnet 4.6, and Claude Haiku 5.5. | Tasks requiring the deepest possible reasoning and most thorough analysis |

247| `xhigh` | Extended capability for long-horizon work. Available on Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Sonnet 5.5, Claude Sonnet 5, and Claude Haiku 5.5. | Long-running agentic and coding tasks (over 30 minutes) with token budgets in the millions |

248| `high` | Spends as many tokens as the task needs for excellent results. The default on every model that supports effort except Claude Opus 5.5 and Claude Haiku 5.5. | Complex reasoning, difficult coding problems, agentic tasks |

249| `medium` | Balanced approach with moderate token savings. The default on Claude Opus 5.5 and Claude Haiku 5.5. | Agentic tasks that require a balance of speed, cost, and performance |

250| `low` | Most efficient. Significant token savings with some capability reduction. | Simpler tasks that need the best speed and lowest costs, such as subagents |

246| Level | Description | Typical use case |

247| -------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------ |

248| `max` | Absolute maximum capability with no constraints on token spending. Available on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Mythos Preview, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Opus 4.6, Claude Sonnet 5.5, Claude Sonnet 5, Claude Sonnet 4.6, and Claude Haiku 5.5. | Tasks requiring the deepest possible reasoning and most thorough analysis |

249| `xhigh` | Extended capability for long-horizon work. Available on Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Fable 5, Claude Mythos 5, Claude Opus 5.5, Claude Opus 5, Claude Opus 4.8, Claude Opus 4.7, Claude Sonnet 5.5, Claude Sonnet 5, and Claude Haiku 5.5. | Long-running agentic and coding tasks (over 30 minutes) with token budgets in the millions |

250| `high` | Spends as many tokens as the task needs for excellent results. The default on every model that supports effort except Claude Opus 5.5 and Claude Haiku 5.5. | Complex reasoning, difficult coding problems, agentic tasks |

251| `medium` | Balanced approach with moderate token savings. The default on Claude Opus 5.5 and Claude Haiku 5.5. | Agentic tasks that require a balance of speed, cost, and performance |

252| `low` | Most efficient. Significant token savings with some capability reduction. | Simpler tasks that need the best speed and lowest costs, such as subagents |

251253

252254Not every model that supports `max` supports `xhigh`.

253255

from line 261

259261

260262## Recommended effort levels

261263

262**[Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) & [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview)** — *For demanding reasoning and long-horizon agentic work*

264**[Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview) & [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview)** — *For demanding reasoning and long-horizon agentic work*

263265

264Claude Fable 5.1 supports all five effort levels. **Start with `high`, the default.** Step up to `xhigh` or `max` for the most capability-sensitive agentic and coding work, and step down to `medium` or `low` for routine or latency-sensitive work once your evals show quality holds. At `high` and above, set a large `max_tokens`. It’s a hard limit on total output (thinking plus response text).

266Claude Fable 5.2 supports all five effort levels. The API default is `high`. Adaptive thinking is always on, so effort is your main control for thinking depth, latency, and cost. Start with `high`. Most of the gain in capability is already present at `high`, and above it, gains are uneven and depend on the task. Step up to `xhigh` for your hardest long-running coding and agentic work, where you’ve measured a gain. Step down to `medium` or `low` where your evals show quality holds. Reserve `max` for measuring the model’s ceiling and for the rare task where time and tokens don’t matter. At `max` the model optimizes for capability without regard to token cost. It runs slower and costs more than at `xhigh`, often for only a small gain. Run an effort sweep on your own evals rather than carrying settings over from Claude Fable 5.1. At `high` and above, set a large `max_tokens`. It’s a hard limit on total output (thinking plus response text). Effort barely changes how long the model’s replies are, so use your prompt to change reply length and tone. The same recommendations apply to Claude Mythos 5.2.

265267

266Claude Fable 5.1 also supports [changing effort mid-conversation](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) with a per-message `output_config`, which preserves the prompt cache.

268Where your platform supports it, Claude Fable 5.2 and Claude Mythos 5.2 also support [changing effort mid-conversation](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) with a per-message `output_config`, which preserves the prompt cache.

267269

268See also: [Prompting Claude Fable 5.1](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1#consider-all-effort-levels)

270See also: [Prompting Claude Fable 5.2](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-2#calibrate-effort)

269271

270272**[Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview)** — *For long-running agentic coding and knowledge work*

271273

from line 295

293295

294296See also: [Prompting Claude Haiku 5.5](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-haiku-5-5#use-effort-to-control-thinking)

295297

298**[Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview) & [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview)**

299

300Claude Fable 5.1 supports all five effort levels. **Start with `high`, the default.** Step up to `xhigh` or `max` for the most capability-sensitive agentic and coding work, and step down to `medium` or `low` for routine or latency-sensitive work once your evals show quality holds. At `high` and above, set a large `max_tokens`. It’s a hard limit on total output (thinking plus response text).

301

302Claude Fable 5.1 also supports [changing effort mid-conversation](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) with a per-message `output_config`, which preserves the prompt cache.

303

304See also: [Prompting Claude Fable 5.1](https://platform.claude.com/docs/en/build-with-claude/prompt-engineering/prompting-claude-fable-5-1#consider-all-effort-levels)

305

296306**[Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview) & [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview)**

297307

298308Effort is the primary control for trading off intelligence, latency, and cost on Claude Fable 5. **Start with `high`, the default, for most tasks**, use `xhigh` for the most capability-sensitive workloads, and step down to `medium` or `low` for routine work. Lower effort settings on Claude Fable 5 still perform well and often exceed `xhigh` performance on prior models. At `high` and `xhigh`, set a large `max_tokens`. It’s a hard limit on total output (thinking plus response text). See [Cost control](https://platform.claude.com/docs/en/build-with-claude/thinking-steering-and-cost#cost-control).

from line 406

396406

397407## Change effort mid-conversation

398408

399You can run later turns of a conversation at a different effort level in two ways. On Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5, use a per-message effort change, which keeps the prompt cache. On other models, set a new top-level value on the next request, which starts the cache over.

409You can run later turns of a conversation at a different effort level in two ways. On Claude Fable 5.2, Claude Mythos 5.2, Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5, use a per-message effort change, which keeps the prompt cache. On other models, set a new top-level value on the next request, which starts the cache over.

400410

401411### Per-message effort (beta)

402412

403Per-message effort is in beta. On the Claude API and [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), it’s available on Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5. On [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed) and [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), it’s available on Claude Fable 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5. On [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), it’s available on Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5.5. It requires the [beta header](https://platform.claude.com/docs/en/api/beta-headers) `mid-conversation-output-config-2026-07-01`. With the Amazon Bedrock [InvokeModel API](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), it’s available on Claude Fable 5.1 and Claude Opus 5.5, and you send that value in the `anthropic_beta` array of the request body instead.

413Per-message effort is in beta. On the Claude API and [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), it’s available on Claude Fable 5.1, Claude Mythos 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5. On the Claude API, it’s also available on Claude Fable 5.2 and Claude Mythos 5.2. On Claude Models on Google Cloud (Google managed), it’s also available on Claude Fable 5.2 and Claude Mythos 5.2. On [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed) and [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), it’s available on Claude Fable 5.2, Claude Fable 5.1, Claude Opus 5.5, Claude Opus 5, Claude Sonnet 5.5, and Claude Haiku 5.5. On [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), it’s available on Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5.5. It requires the [beta header](https://platform.claude.com/docs/en/api/beta-headers) `mid-conversation-output-config-2026-07-01`. With the Amazon Bedrock [InvokeModel API](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), it’s available on Claude Fable 5.1 and Claude Opus 5.5, and you send that value in the `anthropic_beta` array of the request body instead.

404414

405415Without the beta value, a per-message `output_config` returns a 400 error: `messages.N.output_config: Extra inputs are not permitted`, where `N` is the index of the `system` message in `messages`. With the beta value, models without per-message effort, including Claude Fable 5, return a 400 error: `output_config.effort requires a model that supports per-turn effort; this model does not`. On Amazon Bedrock, those models and Claude Opus 5 return the `Extra inputs are not permitted` error instead. On Claude Sonnet 5.5 with `thinking: {"type": "between_tools"}` and on Claude Haiku 5.5 with `thinking: {"type": "disabled"}`, effort can’t change mid-conversation: a per-message `output_config.effort` that differs from the level in effect returns a 400 error. To vary effort for each turn, use adaptive thinking.

406416

from line 727

717727* Availability: Always on

718728* Usage: Set `output_config.effort` on the request. With no value, the model’s default level applies.

719729

720| Status | Cloud platforms | Models |

721| --------- | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

722| Available | All supported platforms | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview) |

730| Status | Cloud platforms | Models |

731| --------- | ----------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

732| Available | All supported platforms | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview) |

723733

724734#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

725735

from line 736

726736* Availability: Always on

727737* Usage: Set `effort` on the agent’s model object, or in a session’s model override. With no value, Managed Agents fills in the model’s default.

728738

729| Status | Cloud platforms | Models |

730| --------- | ------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

731| Available | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview) |

739| Status | Cloud platforms | Models |

740| --------- | ------------------------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

741| Available | Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) | [Claude Fable 5.2](https://platform.claude.com/docs/en/models/fable-5-2/overview), [Claude Mythos 5.2](https://platform.claude.com/docs/en/models/mythos-5-2/overview), [Claude Fable 5.1](https://platform.claude.com/docs/en/models/fable-5-1/overview), [Claude Mythos 5.1](https://platform.claude.com/docs/en/models/mythos-5-1/overview), [Claude Fable 5](https://platform.claude.com/docs/en/models/fable-5/overview), [Claude Mythos 5](https://platform.claude.com/docs/en/models/mythos-5/overview), Claude Mythos Preview, [Claude Opus 5.5](https://platform.claude.com/docs/en/models/opus-5-5/overview), [Claude Opus 5](https://platform.claude.com/docs/en/models/opus-5/overview), [Claude Sonnet 5.5](https://platform.claude.com/docs/en/models/sonnet-5-5/overview), [Claude Sonnet 5](https://platform.claude.com/docs/en/models/sonnet-5/overview), [Claude Haiku 5.5](https://platform.claude.com/docs/en/models/haiku-5-5/overview), [Claude Opus 4.8](https://platform.claude.com/docs/en/models/opus-4-8/overview), [Claude Opus 4.7](https://platform.claude.com/docs/en/models/opus-4-7/overview), [Claude Opus 4.6](https://platform.claude.com/docs/en/models/opus-4-6/overview), [Claude Sonnet 4.6](https://platform.claude.com/docs/en/models/sonnet-4-6/overview), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview) |

732742

733743### Data handling

734744