Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover safety (readOnlyHint=true, openWorldHint=false), and the description adds substantive context beyond them: substring matching, most-transcribed-first ranking, a hard cap of 20 results, and no auth/key requirement with no cost. It omits matching case-sensitivity and whether truncated result sets can be paged.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.