Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already signal readOnlyHint=true, and the description adds useful behavioral context: the search is full-text, scoped to one channel, and shares access rules with freeq_history. It does not describe edge cases or result ordering, but the output schema reduces the need for that.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.