Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate a safe, read-only, idempotent operation. The description adds context about the underlying data source (data.gov.au CKAN Action API) and the absence of authentication, which is beyond the annotations. It also discloses the specific output fields, providing useful behavioral information without contradicting 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.