Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Given no annotations providing safety details, the description carries the full burden, and it delivers: it discloses cancellation sends attendee email and fires booking.cancelled, while completed/no_show are internal and contact no one. It also states precondition requirements, going well beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.