Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and destructiveHint:false, covering the safety profile. The description adds valuable behavioral context by specifying the input format ('5 fields or an @alias') and the return behavior ('Returns the parsed fields and whether it is valid'). No contradiction with annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.