Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the safe read-only/idempotent profile, and the description adds real value beyond them: the non-test eligibility filter, the 30-day UTC default when dates are omitted, the backend-resolved default app, and that the applied scope is echoed back. It stops short of noting pagination or billing/eligibility edge cases.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.