Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, non-destructive behavior, but the description adds real value beyond them: the result is capped at 20 events, and official-website fields in directory metadata are explicitly flagged as not automatically verified sources — a meaningful trust caveat for consumers of this data.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.