Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds meaningful context beyond annotations by clarifying output semantics: canonical names, group membership preservation, and the distinction between domestic league and grouped tournament naming.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.