Under the hood
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Tool descriptions can now be marked as deferred and built through a new describe-hooks step
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.
Names in the bundlewithoutToolDescribeHooks
Something disagreesSomething we can check disagrees with this entry, or the writer said they could not settle it.
The writer flagged doubt
It isn't clear which tools use deferred descriptions or what a user would observe differently as a result.