Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full behavioral burden and does not deliver it: it does not say whether unassignment is reversible, whether notifications are sent, what permission level is required, or what happens if the user is not currently assigned. Only the bare mutation is implied.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.