Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare the tool as read-only, idempotent, and non-destructive, lowering the burden. The description adds value by specifying exactly what counters are included (verification rate, confidence, source count, urgency, actionability breakdowns), giving the agent a clear picture of the response content beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.