Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and idempotentHint=false, so the safety profile is covered. The description adds the useful scope detail that only joined groups are returned, plus the fields in the response, but says nothing about pagination, result limits, or behavior for accounts with no groups.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.