Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: what the response contains, what it deliberately omits, and a UX rule about presenting names/locales instead of UUIDs.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.