Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden; it does communicate a read-only lookup ('조회합니다'), the one-of identifier constraint, and the days default/max. However, it does not disclose what happens if both or neither identifier is supplied, whether one takes precedence, error behavior, or any rate/source limitations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.