Nothing to try yetTier: how much it should matter to you
5Useful: my rating, 1 to 5
4Signal: worth watching, 1 to 5
Advisor ToolArea: what it touches
In DevelopmentKind: in v2.1.265,
What probably matters to youSection of the release
Unclear What event or feature the "advisor_tool" category actually classifies is not stated.
What
A new "advisor tool" mechanism has been added. It can send the model an attachment (attachment.type === "advisor_tool") telling it whether an advisor tool is or isn't currently available, with messages like "The advisor tool is no longer available" or "is available". A new "advisor_tool" category token was also added to several of the internal lists used for telemetry and context-injection categorization, alongside existing tokens like remote_session_change.
Why
The feature is controlled by a feature gate and is off by default, so it doesn't affect current sessions, but lays groundwork for Claude to be told when an advisor tool becomes available to it.
The entry above is what we published on the day. These lines were added later, as Anthropic's own pages caught up, and they sit beside the original rather than replacing it.
Added sinceA small documentation edit on advisor-tool touched a line naming advisor_tool after this was published.accDescr: Your application sends a request with the advisor tool to the executor model, which begins the task. The executor emits a server_tool_use block, and Anthropic runs the advisor model server-side. The advisor reads the full transcr…agents-and-tools/tool-use/advisor-toolsee the edit
How sure we are
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubtWhat event or feature the "advisor_tool" category actually classifies is not stated.
Anthropic's documentation agreesA small documentation edit on advisor-tool touched a line naming advisor_tool after this was published.
