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2929Each of these enables the advisor for sessions whose main model [supports it](#choose-an-advisor-model). After the session starts, Claude Code shows an `Advisor Tool (experimental) is on and may use more tokens · /advisor` notification. To stop using the advisor, see [Turn the advisor off](#turn-the-advisor-off).
3030
31On some plans, Fable as the advisor also needs your one-time [consent to bill Fable 5 usage to usage credits](/docs/en/model-config#fable-5-and-usage-credits). For what happens before you have given that consent, see [Fable advisor and usage credits](#fable-advisor-and-usage-credits).
31On some plans, Fable as the advisor also needs your one-time [consent to bill Fable usage to usage credits](/docs/en/model-config#fable-and-usage-credits). For what happens before you have given that consent, see [Fable advisor and usage credits](#fable-advisor-and-usage-credits).
3232
3333### Use the `/advisor` command
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4242
4343Claude Code doesn't invoke a saved advisor that your organization's [`availableModels`](/docs/en/model-config#restrict-model-selection) allowlist excludes. To use the advisor, pick an allowed model with `/advisor`. Claude Code still saves an advisor that your current main model doesn't support. That advisor activates after you switch to a [compatible main model](#choose-an-advisor-model) with [`/model`](/docs/en/model-config#setting-your-model).
4444
45On some plans, Fable as the advisor also needs your one-time [consent to bill Fable 5 usage to usage credits](/docs/en/model-config#fable-5-and-usage-credits). For what `/advisor fable` does before you have given that consent, see [Fable advisor and usage credits](#fable-advisor-and-usage-credits).
45On some plans, Fable as the advisor also needs your one-time [consent to bill Fable usage to usage credits](/docs/en/model-config#fable-and-usage-credits). For what `/advisor fable` does before you have given that consent, see [Fable advisor and usage credits](#fable-advisor-and-usage-credits).
4646
4747### Set `advisorModel` in settings
4848
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7575
7676The advisor must be at least as capable as the main model. The accepted advisors for each main model are:
7777
78| Main model | Accepted advisors | Notes |
79| ------------------- | ---------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
80| Haiku 4.5 | Fable, Opus, Sonnet | Haiku can call the advisor but cannot act as one |
81| Sonnet 4.6 | Fable, Opus, Sonnet | |
82| Sonnet 5 | Fable, Opus, Sonnet 5 | A Sonnet 4.6 advisor is rejected |
83| Opus 4.6 | Fable, Opus, Sonnet 5 | Sonnet 5 and Opus 4.6 are ranked as equally capable, so an Opus 4.6 main accepts a Sonnet 5 advisor |
84| Opus 4.7 or later | Fable, and Opus 4.7 or later | Opus 4.7 and later Opus models are ranked as equally capable, so any of them accepts another as an advisor. An Opus 4.7 main with an Opus 4.6 or Sonnet 5 advisor is rejected |
85| Fable 5 (v2.1.170+) | Fable | An Opus or Sonnet advisor is rejected |
78| Main model | Accepted advisors | Notes |
79| -------------------- | ------------------------------------ | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
80| Haiku 4.5 | Fable, Opus, Sonnet | Haiku can call the advisor but cannot act as one |
81| Sonnet 4.6 | Fable, Opus, Sonnet | |
82| Sonnet 5 | Fable, Opus, Sonnet 5 | A Sonnet 4.6 advisor is rejected |
83| Opus 4.6 | Fable, Opus, Sonnet 5 | Sonnet 5 and Opus 4.6 are ranked as equally capable, so an Opus 4.6 main accepts a Sonnet 5 advisor |
84| Opus 4.7 or later | Fable, and Opus 4.7 or later | Opus 4.7 and later Opus models are ranked as equally capable, so any of them accepts another as an advisor. An Opus 4.7 main with an Opus 4.6 or Sonnet 5 advisor is rejected |
85| Fable 5.1 or Fable 5 | Fable 5.1, or the same Fable version | An Opus or Sonnet advisor is rejected, and so is a Fable 5 advisor for a Fable 5.1 main model |
8686
87Fable 5 requires Claude Code v2.1.170 or later and [Fable 5 access](/docs/en/model-config#work-with-fable-5), whether it acts as the main model or the advisor.
87Fable 5.1 requires Claude Code v2.1.255 or later and Fable 5 requires v2.1.170 or later, plus [Fable access](/docs/en/model-config#work-with-fable).
8888
8989Set the advisor as `fable`, `opus`, or `sonnet`. These aliases resolve to Claude Code's built-in default version for each model family, which advances with new Claude Code releases. You can also pass a full model ID such as `claude-opus-5`.
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9797
9898### Fable advisor and usage credits
9999
100On some plans, Fable 5 usage bills to usage credits, and Claude Code asks for your [one-time consent to bill Fable 5 usage to usage credits](/docs/en/model-config#fable-5-and-usage-credits) when you select Fable 5 with `/model`. Fable as the advisor bills the same way, so on those plans Claude Code doesn't apply Fable as the advisor until you have accepted that consent.
100On some plans, Fable usage bills to usage credits, and Fable as the advisor bills the same way. If your account requires the [one-time consent to bill Fable usage to usage credits](/docs/en/model-config#fable-and-usage-credits), Claude Code asks for it when you select a Fable model with `/model` and doesn't apply Fable as the advisor until you have accepted that consent.
101101
102102Before you have accepted it, Claude Code doesn't save Fable as the advisor when you type `/advisor fable` or pick Fable in the `/advisor` picker. It points you to `/model fable` instead. With `claude --advisor fable`, Claude Code exits at launch with a message that points to `/model fable`. In a [background session](#use-the-advisor-flag), it starts the session without the advisor instead of exiting. With Fable already saved as your `advisorModel`, Claude Code sends requests without the advisor. In an interactive session whose main model supports the advisor, it also shows a notification that points to `/model fable`.
103103
104To accept the consent, run `/model fable` and choose to continue on Fable 5. Claude Code records the consent and [saves Fable 5 as your selected model](/docs/en/model-config#default-model-setting). Then select Fable as the advisor.
104To accept the consent, run `/model fable` and choose to continue on Fable. Claude Code records the consent and [saves Fable as your selected model](/docs/en/model-config#default-model-setting). Then select Fable as the advisor.
105105
106106### Common model pairings
107107
108108Any accepted pairing works. These combinations balance cost against capability in different ways:
109109
110| Pairing | When to use |
111| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
112| Sonnet main + Opus advisor | Sonnet handles routine work and escalates planning, ambiguous failures, and completion checks to Opus |
113| Sonnet main + Fable advisor | Fable 5 guidance at decision points without running Fable 5 throughout. Requires v2.1.170 or later and Fable 5 access |
114| Haiku main + Opus advisor | Lowest-cost main model with strong planning. Expect higher cost than Haiku alone but lower than switching the main model to Sonnet or Opus |
115| Opus main + Opus advisor | A second Opus reviews the first. Useful for high-stakes tasks where an independent check matters more than cost |
116| Fable main + Fable advisor | Highest-capability pairing when Fable 5 is available (v2.1.170+). Fable is a higher tier than Opus and Sonnet, so it is the only accepted advisor for a Fable main model |
117| Sonnet main + Sonnet advisor | A lower-cost second opinion for catching routine oversights |
110| Pairing | When to use |
111| ---------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
112| Sonnet main + Opus advisor | Sonnet handles routine work and escalates planning, ambiguous failures, and completion checks to Opus |
113| Sonnet main + Fable advisor | Fable guidance at decision points without running Fable throughout. Requires Fable access |
114| Haiku main + Opus advisor | Lowest-cost main model with strong planning. Expect higher cost than Haiku alone but lower than switching the main model to Sonnet or Opus |
115| Opus main + Opus advisor | A second Opus reviews the first. Useful for high-stakes tasks where an independent check matters more than cost |
116| Fable main + Fable advisor | Highest-capability pairing when Fable is available. Claude Code doesn't apply an Opus or Sonnet advisor to a Fable main model |
117| Sonnet main + Sonnet advisor | A lower-cost second opinion for catching routine oversights |
118118
119119## When Claude consults the advisor
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135135
136136## Cost
137137
138When Claude calls the advisor, the advisor model reads the conversation, so each call consumes tokens at the advisor model's rates in addition to your main model's usage. With API billing, you pay the advisor model's input and output rates for advisor tokens. On subscription plans, advisor usage counts toward your plan's usage limits, except that a Fable 5 advisor bills to [usage credits](/docs/en/model-config#fable-5-and-usage-credits) on plans where Fable 5 usage does. If your account requires the usage-credits consent, a Fable advisor bills nothing before you give it, because Claude Code [doesn't apply the selection](#fable-advisor-and-usage-credits) until then.
138When Claude calls the advisor, the advisor model reads the conversation, so each call consumes tokens at the advisor model's rates in addition to your main model's usage. With API billing, you pay the advisor model's input and output rates for advisor tokens. On subscription plans, advisor usage counts toward your plan's usage limits, except that a Fable advisor bills to [usage credits](/docs/en/model-config#fable-and-usage-credits) on plans where Fable usage does. If your account requires the usage-credits consent, a Fable advisor bills nothing before you give it, because Claude Code [doesn't apply the selection](#fable-advisor-and-usage-credits) until then.
139139
140140Claude calls the advisor at decision points rather than on every turn, so pairing a faster main model with a stronger advisor typically costs less than running the stronger model throughout. Advisor usage counts toward the session totals shown by [`/usage`](/docs/en/costs#track-your-costs).
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152152The advisor tool requires all of the following:
153153
154154* **Anthropic API only**: the advisor is a server-executed tool. It is not available on Amazon Bedrock, Claude Platform on AWS, Google Cloud's Agent Platform, or Microsoft Foundry. Through an [LLM gateway](/docs/en/llm-gateway) configured with `ANTHROPIC_BASE_URL`, availability depends on whether the gateway forwards the request intact to the Anthropic API.
155* **Supported main model**: Opus 4.6 or later, Sonnet 4.6 or later, or Haiku 4.5. Fable 5 also qualifies on Claude Code v2.1.170 or later, and a Fable 5 main [accepts only a Fable advisor](#choose-an-advisor-model).
155* **Supported main model**: Fable, Opus 4.6 or later, Sonnet 4.6 or later, or Haiku 4.5. See [Choose an advisor model](#choose-an-advisor-model) for which advisors each accepts.
156156* **Feature-flag fetching**: Claude Code turns the advisor on through a feature flag it fetches from Anthropic. In a session where a variable that turns flag fetching off is set, such as `DISABLE_TELEMETRY`, the advisor stays off. See [Features that need feature-flag fetching](/docs/en/env-vars#features-that-need-feature-flag-fetching).
157157
158158## Turn the advisor off