Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (idempotent, non-destructive, open-world), so the description's job is to add effect detail — and it does: teammates stop seeing the session and messages stop arriving. It does not say whether the live session can be resumed or what happens to already-sent messages, but the core observable effects are disclosed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.