Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description layers on policy semantics the annotations cannot express: results are 'evidence, not permission', missing/RETIRED answers must not be fabricated, and REFUSED/gap conditions require human review rather than customer promises.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.