Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Beyond the annotations, it discloses notable side effects: 'me' or null to unassign, timeline recording for each change, and one aggregated notification for the whole batch. It also sets the member eligibility constraint, which is behavioral context the annotations don't convey.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.