With /advisor fable in Claude Code, Opus 5.5 checks with Fable 5.1 before it plans and before it calls a task done

Type /advisor fable in Claude Code and Opus 5.5 keeps doing the work, calling Fable in as an advisor only at key moments. The official docs say it tends to consult before committing to an approach, when an error keeps recurring, and before declaring the task done. The advisor receives the full conversation, including every tool call and result, and sends back guidance. The model decides when to call it, and you can ask for a consultation in your prompt, for example "consult the advisor before you continue."

There are three ways to set it: the /advisor command mid-session, the advisorModel setting for a default, or the --advisor flag at launch. Run /advisor alone for a picker and /advisor off to turn it off. Advisor tokens count toward your plan limits, and on some plans a Fable advisor bills to usage credits, so you first give consent with /model fable. It adds little on short tasks and fits long refactors or debugging where the same error keeps coming back.