Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare read-only, idempotent, and non-destructive properties. The description adds useful behavioral context: the external service (Nominatim), a result limit of up to 5, and the specific return fields. This goes beyond the annotation baseline without contradicting it.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.