Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the burden of behavioral disclosure. It does state that all matches are returned, which is useful, but it does not disclose behavior for invalid regex patterns, zero matches, or how flags alter matching semantics. The description is adequate but not transparent about edge cases.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.