Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already flag destructiveHint=true and non-idempotent, but the description adds exactly the context they cannot carry: the login is deleted (sign-in blocked), connected calendars are disconnected, the action is irreversible, and recovery requires re-inviting. It also documents the authorization invariants (owner protected, no self-removal), which are pure behavioral detail.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.