Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark this as readOnly, openWorld, idempotent, and non-destructive, so the bar is lower. The description adds valuable behavioral context: the identity object is the same across sports with null meaning unknown, not wrong sport, and that rankings only nests under tennis while being null elsewhere. This goes beyond the structured annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.