Under the hoodTier: how much it should matter to you
2Useful: my rating, 1 to 5
3Signal: worth watching, 1 to 5
Tool SchemaArea: what it touches
Internal ChangesKind: in v2.1.277,
Internal ChangesSection of the release
Unclear It isn't clear which tools use deferred descriptions or what a user would observe differently as a result.
What
When Claude Code builds a tool's schema and description, a tool can now be marked as having a "deferred" description. Deferred tools now run through a new describe-hooks step during setup, unless a withoutToolDescribeHooks option is set to skip it, and Claude Code records whether the deferred flag actually changed.
Why
This adds a mechanism for building certain tool descriptions later rather than upfront, though the finding doesn't specify which tools use it or what practical difference a reader would notice.
