Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations only cover the safety profile (readOnlyHint false, destructiveHint false, non-idempotent); the description adds genuinely useful behavior the annotations cannot convey: immediate automatic approval, expected timing (typically 2 minutes, occasionally 4), and the report/issue/violator/diagnosis result hierarchy. That is strong added context.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.