Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds genuinely non-schema behavior: newest-first ordering, open-by-default filtering, and the fact that calls do not count against the daily quota, which is useful operational context. It stops short of describing pagination mechanics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.