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advisor-tool changedagents-and-tools/tool-use/advisor-tool

Nearest release: v2.1.293, published an hour before this site recorded the change. Shown because the two are within 24 hours of each other. Nothing here says the release caused the edit.

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Lines−17removed
From line 343 where the diff opens
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Recorded edits13to this page, all time

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343343| `advisor_redacted_result` | `encrypted_content`, `stop_reason` | The advisor model returns encrypted output. |
344344 
345345<Note>
346 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 advisors return the encrypted `advisor_redacted_result`. Every other advisor model in the [compatibility table](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 your executor's row in the [compatibility table](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) lists one. 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.
346 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 the [compatibility table](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 your executor's row in the [compatibility table](https://platform.claude.com/docs/en/agents-and-tools/tool-use/advisor-tool#model-compatibility) lists one. 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.
347347</Note>
348348 
349349Here is the same request sent twice, identical except for the advisor `model` in the tool definition, showing both variants.
from line 1401
14011401**Keep it consistent:** Set `caching` once and leave it for the whole conversation. Toggling it off and on mid-conversation causes cache misses.
14021402 
14031403<Warning>
1404 [`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 extended thinking is enabled without explicit `clear_thinking` configuration, the API defaults to `keep: {type: "thinking_turns", value: 1}`, which triggers this behavior (the default on earlier Opus/Sonnet models and all Haiku models, whereas on Opus 4.5+ and Sonnet 4.6+ the default is to keep all turns). Set `keep: "all"` to preserve advisor cache stability.
1404 [`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 extended thinking is enabled without explicit `clear_thinking` configuration, the API defaults to `keep: {type: "thinking_turns", value: 1}`, which triggers this behavior (the default on earlier Opus/Sonnet models and Haiku models through Claude Haiku 4.5, whereas on Opus 4.5+, Sonnet 4.6+, and Haiku 5.5 the default is to keep all turns). Set `keep: "all"` to preserve advisor cache stability.
14051405</Warning>
14061406 
14071407## Combining with other tools
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18091809 
18101810The 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.
18111811 
1812| Executor models | Advisor models |
1813| ------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
1814| Claude Haiku 4.5 (claude-haiku-4-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Sonnet 4.6 (claude-sonnet-4-6) |
1815| Claude Sonnet 4.6 (claude-sonnet-4-6) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Sonnet 4.6 (claude-sonnet-4-6) |
1816| Claude Sonnet 5 (claude-sonnet-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) |
1817| Claude Sonnet 5.5 (claude-sonnet-5-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1818| Claude Opus 4.6 (claude-opus-4-6) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) |
1819| Claude Opus 4.7 (claude-opus-4-7) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1820| Claude Opus 4.8 (claude-opus-4-8) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1821| Claude Opus 5 (claude-opus-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1822| Claude Opus 5.5 (claude-opus-5-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1823| Claude Fable 5 (claude-fable-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1824| Claude Mythos 5 (claude-mythos-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1825| Claude Fable 5.1 (claude-fable-5-1) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) |
1826| Claude Mythos 5.1 (claude-mythos-5-1) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) |
1812| Executor models | Advisor models |
1813| ------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
1814| Claude Haiku 4.5 (claude-haiku-4-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Sonnet 4.6 (claude-sonnet-4-6) Claude Haiku 5.5 (claude-haiku-5-5) |
1815| Claude Haiku 5.5 (claude-haiku-5-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Haiku 5.5 (claude-haiku-5-5) |
1816| Claude Sonnet 4.6 (claude-sonnet-4-6) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Sonnet 4.6 (claude-sonnet-4-6) Claude Haiku 5.5 (claude-haiku-5-5) |
1817| Claude Sonnet 5 (claude-sonnet-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Haiku 5.5 (claude-haiku-5-5) |
1818| Claude Sonnet 5.5 (claude-sonnet-5-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1819| Claude Opus 4.6 (claude-opus-4-6) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Opus 4.6 (claude-opus-4-6) Claude Sonnet 5.5 (claude-sonnet-5-5) Claude Sonnet 5 (claude-sonnet-5) Claude Haiku 5.5 (claude-haiku-5-5) |
1820| Claude Opus 4.7 (claude-opus-4-7) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1821| Claude Opus 4.8 (claude-opus-4-8) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) Claude Opus 4.8 (claude-opus-4-8) Claude Opus 4.7 (claude-opus-4-7) Claude Sonnet 5.5 (claude-sonnet-5-5) |
1822| Claude Opus 5 (claude-opus-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1823| Claude Opus 5.5 (claude-opus-5-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1824| Claude Fable 5 (claude-fable-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1825| Claude Mythos 5 (claude-mythos-5) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) Claude Mythos 5 (claude-mythos-5) Claude Fable 5 (claude-fable-5) Claude Opus 5.5 (claude-opus-5-5) Claude Opus 5 (claude-opus-5) |
1826| Claude Fable 5.1 (claude-fable-5-1) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) |
1827| Claude Mythos 5.1 (claude-mythos-5-1) | Claude Mythos 5.1 (claude-mythos-5-1) Claude Fable 5.1 (claude-fable-5-1) |
18271828 
18281829If you request an invalid pair, the API returns a `400 invalid_request_error` naming the unsupported combination.
18291830 
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