Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds the 'Unproven' warning and the 'Counts and law only' scope limitation, which are useful beyond annotations, though 'The landlord does not read locker bags' is too oblique to be actionable.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.