Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden, and it delivers substantial context: skip rules for specific directories and large files, and a nuanced fallback (degrade to literal matching, return literal_fallback warning when there are hits, report INVALID_REGEX only on zero hits). This exceeds what the schema provides. Minor gaps remain (return format, case sensitivity), keeping it just below a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.