Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark it read-only, idempotent, and non-destructive, and the description adds genuinely new behavioral facts: newest-first ordering, retrieval of keys and sizes rather than values, and the API-key requirement for private storage. No contradiction with annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.