Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of behavioral disclosure, but it only states the operation and date format. It omits details like inclusive/exclusive range semantics, ordering, pagination, timezone handling, and whether all calendars or a specific calendar is queried. The verb 'List' implies read-only behavior, but no meaningful behavior beyond that is revealed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.