Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark it as read-only, idempotent, and non-destructive. The description adds valuable behavioral details: returns aggregate stats, does not leak secrets or user identities, and specifies error handling for invalid IDs. 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.