Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The description explains important behavioral facets beyond annotations: each change is recorded on the lead timeline, the assignee gets one aggregated notification, and omitting/null clears the assignee. This informs the agent of mutation effects without needing to infer them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.