Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already establish the safety profile (read-only, idempotent, non-destructive), so the bar is lower. The description adds meaning by disambiguating statuses ('Held is not occupied'), but it doesn't disclose behaviors like authentication requirements or failure modes—those live in the parameter schemas.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.