Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and open-world hints, so the bar is lower. The description adds useful behavioral context beyond the annotations: it returns a paginated list, supports an optional media-type filter, and explicitly lists the return fields (title, creator, date, type, thumbnail, direct URL). This goes beyond what the annotations alone convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.