Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries full burden. It discloses auth requirements, lack of extra charge, quota counting, and event persistence. Missing details: failure behavior, rate limits, idempotency, or the meaning of '30-day persistent workflow'.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.