Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, openWorldHint=false and destructiveHint=false, so the safety profile is fully covered without the description. The description adds nothing beyond that — no statement of what is retrieved, whether it 404s for unknown ids, or auth prerequisites. The only added value is the pointer to describe_operation for schemas.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.