Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly/idempotent/non-destructive, and the description adds real context beyond them: the 20-item window, what `more_requests` and `more_requests_hint` report, and the exact pagination contract. It also discloses an auth prerequisite ('needs a connection whose key has a name') and that nothing executes a request.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.