Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and open-world behavior, so the safety profile is covered. The description adds useful behavioral context beyond that: it discloses the data source (RDAP) and the full set of returned fields, including domain age and abuse contact, which helps an agent judge fitness for vetting tasks.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.