Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already establishes that this is a safe, non-mutating call, so the description does not need to cover the safety profile. It does contribute one meaningful behavioral detail beyond the annotation: the result is scoped to whatever the configured credentials can access, which explains why the output may be a subset. It says nothing about pagination, ordering, or return shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.