Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint. The description adds substantial behavioral detail beyond annotations: default limit (25), maximum (200), response budget (~64 KB), cursor behavior ('pass the next_cursor it returned'), and directional ordering ('outgoing first'). It also guarantees 'never truncated', which is a meaningful behavioral promise.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.