api-20261102T163708Z / documentation capture

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2626 supportedPlatforms:

2727 Claude API: stable

2828 Claude Platform on AWS: stable

29 Claude Models on Google Cloud (Anthropic managed): stable

2930 Amazon Bedrock: stable

3031 Amazon Bedrock (InvokeModel): stable

3132 Claude Models on Google Cloud (Google managed): stable

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288289

289290To get less thinking, lower the effort level. You can also send `thinking: {"type": "disabled"}` at `high` effort or below. At `xhigh` or `max`, it returns a 400 error, so use adaptive thinking there: omit the `thinking` field or send `thinking: {"type": "adaptive"}`.

290291

291On the Claude API and Claude Models on Google Cloud (Google managed), Claude Haiku 5.5 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. 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.

292Where your platform supports it, Claude Haiku 5.5 also lets you [change 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. 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.

292293

293294See 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)

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399400

400401### Per-message effort (beta)

401402

402Per-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 [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.

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.

403404

404405Without 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.

405406

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716717* Availability: Always on

717718* Usage: Set `output_config.effort` on the request. With no value, the model’s default level applies.

718719

719| Status | Cloud platforms | Models |

720| --------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |

721| Available | 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), [Claude Opus 4.5](https://platform.claude.com/docs/en/models/opus-4-5/overview) |

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) |

722723

723724#### [Managed Agents](https://platform.claude.com/docs/en/managed-agents/overview)

724725

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521521

522522 * [Prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching)

523523 * [Extended thinking](https://platform.claude.com/docs/en/build-with-claude/thinking)

524 * [Adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking#configuring-thinking)

525 * [Effort](https://platform.claude.com/docs/en/build-with-claude/effort)

524526 * [Server-side fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#server-side-fallback)

525527 * [Streaming](https://platform.claude.com/docs/en/build-with-claude/streaming)

526528 * [Structured outputs](https://platform.claude.com/docs/en/build-with-claude/structured-outputs)

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315315* `budget_tokens` can exceed `max_tokens` here; the [budget rules](https://platform.claude.com/docs/en/build-with-claude/extended-thinking#budget-rules-and-tuning) explain this exception.

316316* Interleaved thinking is only supported for [tools used through the Messages API](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview).

317317

318How platforms treat the beta header differs. The Claude API and [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws) accept `interleaved-thinking-2025-05-14` on any model and ignore it where unsupported. Acceptance is not the same as effect: on models that reject `type: "enabled"` (4.7 and later) or lack manual-mode interleaving (Claude Opus 4.6), the header has no manual-mode effect; adaptive thinking interleaves automatically there.

318How platforms treat the beta header differs. The Claude API, [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), and [Claude Models on Google Cloud (Anthropic managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/anthropic-managed) accept `interleaved-thinking-2025-05-14` on any model and ignore it where unsupported. Acceptance is not the same as effect: on models that reject `type: "enabled"` (4.7 and later) or lack manual-mode interleaving (Claude Opus 4.6), the header has no manual-mode effect; adaptive thinking interleaves automatically there.

319319

320320Partner-operated platforms, [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock) and [Claude Models on Google Cloud (Google managed)](https://platform.claude.com/docs/en/build-with-claude/claude-models-on-google-cloud/google-managed), likewise accept the header on any model without returning an error, and ignore it on models that don’t support interleaved thinking.

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16591659

16601660You can still set the top-level `system` field for instructions that should apply to the entire conversation. Reserve mid-conversation system messages for instructions that only become relevant later, or that you want to add without invalidating the cached prefix.

16611661

1662A `role: "system"` message can also carry `output_config.effort` to change the [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level partway through a conversation. This is in beta 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 and Claude Models on Google Cloud (Google managed), and requires the `mid-conversation-output-config-2026-07-01` beta header. On Amazon Bedrock, it’s in beta on Claude Fable 5.1, Claude Mythos 5.1, and Claude Opus 5.5, with the same beta value. Claude Opus 5 doesn’t support it on Amazon Bedrock. See [Per-message effort](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta).

1662A `role: "system"` message can also carry `output_config.effort` to change the [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level partway through a conversation, in beta. See [Per-message effort](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta).

16631663

16641664<CodeGroup>

16651665 ```bash cURL

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12531253

12541254### Change effort with a per-message `output_config`

12551255

1256Changing top-level `output_config.effort` between requests doesn’t invalidate thinking, because effort isn’t part of the prefix. Changing top-level effort does restart the prompt cache. Where the model and platform support [per-message effort](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta), use it instead: append a `role: "system"` message with empty `content` and the new level. It needs the beta header `mid-conversation-output-config-2026-07-01`. On Claude Haiku 5.5, per-message effort is available on the Claude API and Claude Models on Google Cloud (Google managed) and needs adaptive thinking.

1256Changing top-level `output_config.effort` between requests doesn’t invalidate thinking, because effort isn’t part of the prefix. Changing top-level effort does restart the prompt cache. Where the model and platform support [per-message effort](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta), use it instead: append a `role: "system"` message with empty `content` and the new level. It needs the beta header `mid-conversation-output-config-2026-07-01`. On Claude Haiku 5.5, per-message effort needs adaptive thinking.

12571257

12581258```json

12591259{ "role": "system", "content": [], "output_config": { "effort": "low" } }

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3838* Thinking is on by default and counts toward `max_tokens`, which can go up to 128,000. A `max_tokens` value sized for Claude Haiku 4.5 requests that ran without thinking can cut the reply off, so leave room for thinking.

3939* To get less thinking, lower the effort level. In Anthropic’s testing, telling the model in the prompt to answer directly didn’t stop it from thinking. You can also turn thinking off with `thinking: {"type": "disabled"}`. This works at `low`, `medium`, and `high` only. At `xhigh` and `max`, the request returns a 400 error.

4040* At `xhigh` effort in multi-turn chats, the model sometimes writes its whole answer in its thinking and ends the turn with no visible text. If you see this behavior, check each response for an empty reply.

41* Changing the top-level `effort` value between requests invalidates the prompt cache for the conversation’s messages. On the Claude API and Claude Models on Google Cloud (Google managed), you can change the level partway through a conversation with a [per-message effort change](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) (beta), which keeps the cache. A change holds for every later turn until another one replaces it. It needs the `mid-conversation-output-config-2026-07-01` beta header and adaptive thinking, which is the default. With thinking off, a per-message effort change returns a 400 error.

41* Changing the top-level `effort` value between requests invalidates the prompt cache for the conversation’s messages. Where your platform supports it, you can change the level partway through a conversation with a [per-message effort change](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) (beta), which keeps the cache. A change holds for every later turn until another one replaces it. It needs the `mid-conversation-output-config-2026-07-01` beta header and adaptive thinking, which is the default. With thinking off, a per-message effort change returns a 400 error.

4242

4343## Accurate search results

4444

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9696

9797Per-message steering is useful when only some requests in a conversation warrant extended reasoning. An agent harness, for example, can append the encouraging phrase on planning steps and the discouraging phrase on routine confirmations, without touching the system prompt or changing any request parameters between turns.

9898

99On Claude Haiku 5.5, the discouraging phrase doesn’t reliably reduce thinking. On the Claude API and Claude Models on Google Cloud (Google managed), run routine turns on that model with less thinking by using a [per-message effort change](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) (beta) instead, which also keeps the prompt cache.

99On Claude Haiku 5.5, the discouraging phrase doesn’t reliably reduce thinking. Where your platform supports it, run routine turns on that model with less thinking by using a [per-message effort change](https://platform.claude.com/docs/en/build-with-claude/effort#change-effort-mid-conversation-beta) (beta) instead, which also keeps the prompt cache.

100100

101101### Verify steering on your workload

102102

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13791379 </Accordion>

13801380

13811381 <Accordion title="Can I delete images I’ve uploaded?">

1382 No. Image uploads are ephemeral and not stored beyond the duration of the API request. Uploaded images are automatically deleted after they have been processed.

1382 No. See [API and data retention](https://platform.claude.com/docs/en/manage-claude/api-and-data-retention) for how long images are kept. If you upload images with the [Files API](https://platform.claude.com/docs/en/build-with-claude/files), you can delete them there.

13831383 </Accordion>

13841384

13851385 <Accordion title="Where can I find details on data privacy for image uploads?">

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8888

8989### Change effort mid-conversation (beta)

9090

91On Claude Fable 5.1 you can change the [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level mid-conversation without invalidating the prompt cache. Raise it for a hard step and lower it for routine ones. Per-message effort is in beta: include the `mid-conversation-output-config-2026-07-01` beta header. Claude Fable 5.1 and Claude Mythos 5.1 support it on the Claude API, Claude Models on Google Cloud (Google managed), and Amazon Bedrock. To use it with Claude Fable 5.1 through the Amazon Bedrock [InvokeModel API](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), send that value in the `anthropic_beta` array of the request body instead. For the other models that support it and the platforms for each, see [Change effort mid-conversation](https://platform.claude.com/docs/en/build-with-claude/effort#changing-effort-mid-conversation).

91On Claude Fable 5.1 you can change the [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level mid-conversation without invalidating the prompt cache. Raise it for a hard step and lower it for routine ones. Per-message effort is in beta: include the `mid-conversation-output-config-2026-07-01` beta header. To use it with Claude Fable 5.1 through the Amazon Bedrock [InvokeModel API](https://platform.claude.com/docs/en/build-with-claude/claude-on-amazon-bedrock-legacy), send that value in the `anthropic_beta` array of the request body instead. For the models and platforms that support it, see [Change effort mid-conversation](https://platform.claude.com/docs/en/build-with-claude/effort#changing-effort-mid-conversation).

9292

9393<CodeGroup>

9494 ```bash cURL

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