Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and closed-world behavior, so the safety profile is covered. The description adds genuine context beyond that: the set of lifecycle states it can report and a privacy guarantee that only the statement and dates are returned, never e-mail, the hidden limit, or other personal data.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.