Unclear The actual numeric limits on hook count and matcher length are not given.
What
A skill is a packaged set of instructions Claude can use, and it can declare hooks: small rules that run when Claude is about to use a tool, for example to block it. Claude Code now checks a skill's hooks against limits on:
- how many hooks there are
- how many characters each hook's matcher (the pattern saying which tools it applies to) has
- whether each matcher can be tested
If a skill goes over any limit, it registers none of its hooks and grants no tools, and Claude Code logs a warning.
Why
A skill that relies on hooks to block certain tools can lose all of them. Claude is told to let you know when this happens, so watch for that notice if you write skills with many or complex hooks.
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The actual numeric limits on hook count and matcher length are not given.