Or, for the model with the same capabilities and no access approval requirement: changedabout-claude/models/migration-guide
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2020
2121## Migrating to Claude Mythos 5 and Claude Fable 5
2222
23[Claude Fable 5](https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5) is Anthropic's most capable widely released model, generally available on the Claude API, [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Google Cloud](https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai), and [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry). [Claude Mythos 5](https://anthropic.com/glasswing) shares the same capabilities and is offered in limited availability to approved customers in Project Glasswing.
23[Claude Fable 5](https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5) is Anthropic's most capable widely released model, available on the Claude API, [Amazon Bedrock](https://platform.claude.com/docs/en/build-with-claude/claude-in-amazon-bedrock), [Claude Platform on AWS](https://platform.claude.com/docs/en/build-with-claude/claude-platform-on-aws), [Google Cloud](https://platform.claude.com/docs/en/build-with-claude/claude-on-vertex-ai), and [Microsoft Foundry](https://platform.claude.com/docs/en/build-with-claude/claude-in-microsoft-foundry). [Claude Mythos 5](https://anthropic.com/glasswing) shares the same capabilities and is offered only to approved customers in Project Glasswing.
2424
2525The baseline settings shared by `claude-fable-5` and `claude-mythos-5`:
2626
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3232
3333Where the two models diverge:
3434
35* **Availability:** Claude Fable 5 is generally available. Claude Mythos 5 is available only to approved customers in [Project Glasswing](https://anthropic.com/glasswing).
35* **Availability:** Claude Fable 5 does not require access approval. Claude Mythos 5 is available only to approved customers in [Project Glasswing](https://anthropic.com/glasswing).
3636* **Safety classifiers:** Claude Fable 5 runs safety classifiers that can decline requests with `stop_reason: "refusal"`. Claude Mythos 5 does not include these classifiers. See [Refusals and fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback).
3737* **Priority Tier:** [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is supported on Claude Fable 5 but not on Claude Mythos 5.
3838
3939### Migrating to Claude Mythos 5 and Claude Fable 5 from Claude Mythos Preview
4040
41[Claude Mythos 5](https://anthropic.com/glasswing) is the access-gated successor to [Claude Mythos Preview](https://anthropic.com/glasswing), the invitation-only research preview. [Claude Fable 5](https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5) is the generally available model with the same capabilities, and the changes in this section apply equally to both targets.
41[Claude Mythos 5](https://anthropic.com/glasswing) is the access-gated successor to [Claude Mythos Preview](https://anthropic.com/glasswing), the invitation-only research preview. [Claude Fable 5](https://platform.claude.com/docs/en/about-claude/models/introducing-claude-fable-5-and-claude-mythos-5) offers the same capabilities and does not require access approval. The changes in this section apply equally to both targets.
4242
4343Migration is mostly drop-in. Claude Mythos 5 and Claude Fable 5 use the same [Messages API](https://platform.claude.com/docs/en/build-with-claude/working-with-messages) and the same [tool use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview) patterns as Claude Mythos Preview, and token counts are roughly unchanged because all three models use the same tokenizer. The key changes to check are the features that are no longer available (listed in the next section) and thinking output. If you migrate to Claude Fable 5, also plan for safety classifier refusals, which Claude Mythos Preview and Claude Mythos 5 do not have; see [Refusals and fallback](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback).
4444
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5050model = "claude-mythos-preview" # Before
5151model = "claude-mythos-5" # After
5252
53# Or, for the generally available model with the same capabilities:
53# Or, for the model with the same capabilities and no access approval requirement:
5454model = "claude-fable-5" # After
5555```
5656
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319319
320320#### Migration checklist
321321
322* Update the model name from `claude-mythos-preview` to `claude-mythos-5`, or to `claude-fable-5` for the generally available model.
322* Update the model name from `claude-mythos-preview` to `claude-mythos-5`, or to `claude-fable-5`, which offers the same capabilities and does not require access approval.
323323* Remove manual extended thinking configuration (`thinking: {type: "enabled", budget_tokens: N}`). Adaptive thinking is always on, and no `thinking` field is required.
324324* Remove any `thinking: {type: "disabled"}` configuration. Disabling thinking returns an error on `claude-mythos-5` and `claude-fable-5`.
325325* Remove `budget_tokens`. It has no direct replacement: thinking is adaptive, and the `effort` parameter is a separate output-level control, not a thinking budget.
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794794
795795### Migrating to Claude Opus 5 from Claude Opus 4.7
796796
797Claude Opus 5 should have strong out-of-the-box performance on existing Claude Opus 4.7 prompts and evals, at the same pricing of $5 per million input tokens and $25 per million output tokens. It supports the same set of features as Claude Opus 4.7, including the [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows), [128k max output tokens](https://platform.claude.com/docs/en/about-claude/models/overview), [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking), [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching), [batch processing](https://platform.claude.com/docs/en/build-with-claude/batch-processing), the [Files API](https://platform.claude.com/docs/en/build-with-claude/files), [PDF support](https://platform.claude.com/docs/en/build-with-claude/pdf-support), [vision](https://platform.claude.com/docs/en/build-with-claude/vision), and server-side and client-side [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview), with two exceptions: [web fetch](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool) is not available on Claude Opus 5, and [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not supported on Claude Opus 5. It also adds [mid-conversation system messages](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages) and publicly documents [refusal stop details](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response). On the Claude API, Claude Opus 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the generally available `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Opus 4.7 supports; existing integrations on the earlier `computer_20251124` version continue to work unchanged on both models. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124).
797Claude Opus 5 should have strong out-of-the-box performance on existing Claude Opus 4.7 prompts and evals, at the same pricing of $5 per million input tokens and $25 per million output tokens. It supports the same set of features as Claude Opus 4.7, including the [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows), [128k max output tokens](https://platform.claude.com/docs/en/about-claude/models/overview), [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking), [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching), [batch processing](https://platform.claude.com/docs/en/build-with-claude/batch-processing), the [Files API](https://platform.claude.com/docs/en/build-with-claude/files), [PDF support](https://platform.claude.com/docs/en/build-with-claude/pdf-support), [vision](https://platform.claude.com/docs/en/build-with-claude/vision), and server-side and client-side [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview), with two exceptions: [web fetch](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool) is not available on Claude Opus 5, and [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not supported on Claude Opus 5. It also adds [mid-conversation system messages](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages) and publicly documents [refusal stop details](https://platform.claude.com/docs/en/build-with-claude/refusals-and-fallback#refusal-response). On the Claude API, Claude Opus 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the stable `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Opus 4.7 supports; existing integrations on the earlier `computer_20251124` version continue to work unchanged on both models. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124).
798798
799799<Note>
800800 If your code is on Claude Opus 4.6 or earlier, use [Migrating to Claude Opus 5 from Claude Opus 4.6 and earlier Opus models](https://platform.claude.com/docs/en/about-claude/models/migration-guide#migrating-from-claude-opus-46) instead. That section includes breaking changes (sampling parameters rejected, manual extended thinking rejected, new tokenizer) that the upgrade from Claude Opus 4.7 alone does not cover.
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855855
856856The following items are not breaking changes; they describe behavior differences worth checking after you swap the model ID.
857857
8581. **Sampling parameters (unchanged):** Setting `temperature`, `top_p`, or `top_k` to a non-default value returns a 400 error on Claude Opus 5, the same as on Claude Opus 4.7. The SDK request types still define these fields for compatibility with earlier models, so code that sets them type-checks, but the API rejects the request server-side. If you removed these parameters when migrating to Opus 4.7, no further changes are needed.
8581. **Sampling parameters (unchanged):** Setting `temperature`, `top_p`, or `top_k` to a non-default value returns a 400 error on Claude Opus 5, the same as on Claude Opus 4.7. Most SDKs still define these fields for compatibility with earlier models, so code that sets them type-checks even though the API rejects the request. The Python SDK (v1.0 and later) does not define them, and passing them raises a `TypeError`. If you removed these parameters when migrating to Opus 4.7, no further changes are needed.
859859
8608602. **Effort default is `high`:** The [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) default on Claude Opus 5 is `high` on the Claude API and Claude Code. If you already set effort explicitly, your setting is unchanged.
861861
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915915* [Vision](https://platform.claude.com/docs/en/build-with-claude/vision)
916916* Server-side and client-side [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview) ([bash](https://platform.claude.com/docs/en/agents-and-tools/tool-use/bash-tool), [code execution](https://platform.claude.com/docs/en/agents-and-tools/tool-use/code-execution-tool), [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool), [text editor](https://platform.claude.com/docs/en/agents-and-tools/tool-use/text-editor-tool), [web search](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-search-tool), [MCP connector](https://platform.claude.com/docs/en/agents-and-tools/mcp-connector), [memory](https://platform.claude.com/docs/en/agents-and-tools/tool-use/memory-tool))
917917
918Two exceptions: [web fetch](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool) is not available on Claude Opus 5, and [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not supported on Claude Opus 5. On the Claude API, Claude Opus 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the generally available `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Opus 4.6 or earlier Opus models support; existing integrations on the earlier `computer_20251124` version continue to work unchanged on Claude Opus 5. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124).
918Two exceptions: [web fetch](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool) is not available on Claude Opus 5, and [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not supported on Claude Opus 5. On the Claude API, Claude Opus 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the stable `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Opus 4.6 or earlier Opus models support; existing integrations on the earlier `computer_20251124` version continue to work unchanged on Claude Opus 5. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124).
919919
920920#### Update your model name
921921
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12161216
121712173. **Disabling thinking is capped at `high` effort:** You can turn thinking off with `thinking: {type: "disabled"}`, but only at an [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level of `high` or below. A request that combines `thinking: {type: "disabled"}` with effort `xhigh` or `max` returns a 400 error on Claude Opus 5, enforced on each request. Audit requests that disable thinking before you migrate: re-enable thinking or lower the effort to `high` or below.
12181218
12194. **Sampling parameters removed:** Setting `temperature`, `top_p`, or `top_k` to any non-default value on Claude Opus 4.7 or later models, including Claude Opus 5, returns a 400 error. The safest migration path is to omit these parameters entirely from request payloads. Prompting is the recommended way to guide model behavior on Claude Opus 5. If you were using `temperature = 0` for determinism, note that it never guaranteed identical outputs on prior models.
12194. **Sampling parameters removed:** Setting `temperature`, `top_p`, or `top_k` to any non-default value on Claude Opus 4.7 or later models, including Claude Opus 5, returns a 400 error. The Python SDK (v1.0 and later) does not define them, and passing them raises a `TypeError`. The safest migration path is to omit these parameters entirely from request payloads. Prompting is the recommended way to guide model behavior on Claude Opus 5. If you were using `temperature = 0` for determinism, note that it never guaranteed identical outputs on prior models.
12201220
122112215. **Thinking content omitted by default:** Thinking blocks still appear in the response stream on Claude Opus 4.7 and later models, but their `thinking` field is empty unless you explicitly opt in. This is a silent change from Claude Opus 4.6, where the default was to return summarized thinking text. To restore summarized thinking content, set `thinking.display` to `"summarized"`:
12221222
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16241624 ```
16251625 </CodeGroup>
16261626
1627 Note that the migration also moves from `client.beta.messages.create` to `client.messages.create`. Adaptive thinking and effort are GA features and do not require the beta SDK namespace or any beta headers.
1627 Note that the migration also moves from `client.beta.messages.create` to `client.messages.create`. Adaptive thinking and effort do not require the beta SDK namespace or any beta headers.
16281628
16292. **Remove effort beta header:** The effort parameter is now GA. Remove `betas=["effort-2025-11-24"]` from your requests.
16292. **Remove effort beta header:** The effort parameter does not require a beta header. Remove `betas=["effort-2025-11-24"]` from your requests.
16301630
16313. **Remove fine-grained tool streaming beta header:** Fine-grained tool streaming is now GA. Remove `betas=["fine-grained-tool-streaming-2025-05-14"]` from your requests.
16313. **Remove fine-grained tool streaming beta header:** Fine-grained tool streaming does not require a beta header. Remove `betas=["fine-grained-tool-streaming-2025-05-14"]` from your requests.
16321632
163316334. **Remove interleaved thinking beta header:** Adaptive thinking automatically enables interleaved thinking on Claude Opus 4.7, Opus 4.6, and Sonnet 4.6. Remove `betas=["interleaved-thinking-2025-05-14"]` from your requests. The header is still functional on Sonnet 4.6 with manual extended thinking, but manual mode is deprecated.
16341634
16355. **Migrate to output\_config.format:** If using structured outputs, update `output_format={...}` to `output_config={"format": {...}}`. The old parameter remains functional but is deprecated and will be removed in a future model release.
16355. **Migrate to output\_config.format:** If using structured outputs, update `output_format={...}` to `output_config={"format": {...}}`. The API still accepts the deprecated `output_format` parameter, but it will be removed in a future model release. The Python SDK (v1.0 and later) does not accept `output_format={...}` on `client.beta.messages.create()` or `count_tokens()`. The `output_format=Model` argument of the `parse()` and `stream()` helpers is unchanged.
16361636
16371637#### Migrating from Claude 4.1 or earlier
16381638
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16561656 This is a breaking change when migrating from Claude 3.x models.
16571657 </Warning>
16581658
1659 Starting with Claude Opus 4.7, setting `temperature`, `top_p`, or `top_k` to any non-default value returns a 400 error. The safest migration path is to omit these parameters entirely from requests, and to use prompting to guide the model's behavior. If you were using `temperature = 0` for determinism, note that it never guaranteed identical outputs.
1659 Starting with Claude Opus 4.7, setting `temperature`, `top_p`, or `top_k` to any non-default value returns a 400 error. The Python SDK (v1.0 and later) does not define them, and passing them raises a `TypeError`. The safest migration path is to omit these parameters entirely from requests, and to use prompting to guide the model's behavior. If you were using `temperature = 0` for determinism, note that it never guaranteed identical outputs.
16601660
16611661 <CodeGroup exclude="shell">
16621662 ```python Python
from line 1997
19971997* **BREAKING:** Remove assistant message prefills (returns 400 error); use structured outputs or `output_config.format` instead
19981998* **BREAKING on Opus 4.7:** Replace `thinking: {type: "enabled", budget_tokens: N}` with `thinking: {type: "adaptive"}` plus the [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) (returns 400 on Opus 4.7)
19991999* Verify tool call JSON parsing uses a standard JSON parser
2000* Remove `effort-2025-11-24` beta header (effort is now GA)
2000* Remove `effort-2025-11-24` beta header (the effort parameter does not require it)
20012001* Remove `fine-grained-tool-streaming-2025-05-14` beta header
20022002* Remove `interleaved-thinking-2025-05-14` beta header (adaptive thinking enables interleaved thinking automatically)
20032003* Migrate `output_format` to `output_config.format` (if applicable)
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20272027
202820282. **Disabling thinking is capped at `high` effort:** On Claude Sonnet 5, `thinking: {type: "disabled"}` is accepted at any effort level. On Claude Opus 5, it is accepted only at an [effort](https://platform.claude.com/docs/en/build-with-claude/effort) level of `high` or below; a request that combines `thinking: {type: "disabled"}` with effort `xhigh` or `max` returns a 400 error, enforced on each request. Audit requests that disable thinking before you migrate.
20292029
20303. **Mid-conversation system messages:** Claude Opus 5 accepts `role: "system"` messages immediately after a user turn in the `messages` array (subject to [placement rules](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages#limitations)); Claude Sonnet 5 does not. If you maintain code paths that rebuild the full message history to update instructions, you can simplify them and preserve [prompt cache](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) hits on earlier turns.
20303. **Mid-conversation system messages:** Claude Opus 5 accepts `role: "system"` messages immediately after a user turn in the `messages` array (subject to [placement rules](https://platform.claude.com/docs/en/build-with-claude/mid-conversation-system-messages#limitations)). This feature is not available on Claude Sonnet 5; use the top-level `system` field instead. If you maintain code paths that rebuild the full message history to update instructions, you can simplify them and preserve [prompt cache](https://platform.claude.com/docs/en/build-with-claude/prompt-caching) hits on earlier turns.
20312031
203220324. **Web fetch is not available:** The [web fetch](https://platform.claude.com/docs/en/agents-and-tools/tool-use/web-fetch-tool) tool is available on Claude Sonnet 5 but not on Claude Opus 5.
20332033
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20442044
20452045Claude Sonnet 5 offers the best combination of speed and intelligence in the Claude model family. It builds on Claude Sonnet 4.6.
20462046
2047Claude Sonnet 5 is a drop-in upgrade for Claude Sonnet 4.6, priced at $2/$10 USD per million input/output tokens; see [Pricing](https://platform.claude.com/docs/en/about-claude/pricing) for details. There are two breaking API changes for code already running on Claude Sonnet 4.6: manual extended thinking (`thinking: {type: "enabled", budget_tokens: N}`) and sampling parameters (`temperature`, `top_p`, `top_k`) set to non-default values are no longer accepted and return a 400 error. Use [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) with the [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) instead. Claude Sonnet 5 supports the same set of features as Claude Sonnet 4.6, including the [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows), [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking), [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching), [batch processing](https://platform.claude.com/docs/en/build-with-claude/batch-processing), the [Files API](https://platform.claude.com/docs/en/build-with-claude/files), [PDF support](https://platform.claude.com/docs/en/build-with-claude/pdf-support), [vision](https://platform.claude.com/docs/en/build-with-claude/vision), and the full set of server-side and client-side [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview). On the Claude API, Claude Sonnet 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the generally available `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Sonnet 4.6 supports; existing integrations on the earlier `computer_20251124` version continue to work unchanged on both models. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not available on Claude Sonnet 5. Claude Sonnet 5 also uses a new tokenizer.
2047Claude Sonnet 5 is a drop-in upgrade for Claude Sonnet 4.6, priced at $2/$10 USD per million input/output tokens; see [Pricing](https://platform.claude.com/docs/en/about-claude/pricing) for details. There are two breaking API changes for code already running on Claude Sonnet 4.6: manual extended thinking (`thinking: {type: "enabled", budget_tokens: N}`) and sampling parameters (`temperature`, `top_p`, `top_k`) set to non-default values are no longer accepted and return a 400 error. Use [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking) with the [effort parameter](https://platform.claude.com/docs/en/build-with-claude/effort) instead. Claude Sonnet 5 supports the same set of features as Claude Sonnet 4.6, including the [1M token context window](https://platform.claude.com/docs/en/build-with-claude/context-windows), [adaptive thinking](https://platform.claude.com/docs/en/build-with-claude/thinking), [prompt caching](https://platform.claude.com/docs/en/build-with-claude/prompt-caching), [batch processing](https://platform.claude.com/docs/en/build-with-claude/batch-processing), the [Files API](https://platform.claude.com/docs/en/build-with-claude/files), [PDF support](https://platform.claude.com/docs/en/build-with-claude/pdf-support), [vision](https://platform.claude.com/docs/en/build-with-claude/vision), and the full set of server-side and client-side [tools](https://platform.claude.com/docs/en/agents-and-tools/tool-use/overview). On the Claude API, Claude Sonnet 5 also supports [computer use](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool) as the stable `computer_toolset_20260801` toolset and the [browser use tool](https://platform.claude.com/docs/en/agents-and-tools/tool-use/browser-use-tool) for tasks inside webpages, neither of which Claude Sonnet 4.6 supports; existing integrations on the earlier `computer_20251124` version continue to work unchanged on both models. To upgrade an existing integration, see [Migrate from `computer_20251124`](https://platform.claude.com/docs/en/agents-and-tools/tool-use/computer-use-tool#migrate-from-computer-20251124). [Priority Tier](https://platform.claude.com/docs/en/api/service-tiers#supported-models) is not available on Claude Sonnet 5. Claude Sonnet 5 also uses a new tokenizer.
20482048
20492049### Migrating to Claude Sonnet 5 from Claude Sonnet 4.6
20502050
from line 2104
21042104 ```
21052105
21062106 ```bash CLI
2107 ant messages create \
2108 --transform content --format yaml <<'YAML'
2107 ant messages create --transform content --format yaml <<'YAML'
21092108 model: claude-sonnet-5
21102109 max_tokens: 16000
21112110 thinking:
No line in this hunk matches that.