Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden of disclosing behavior, but it only names the resource. It does not state whether the call is read-only, what kinds of status data are returned, whether any side effects occur, or whether authentication or system state dependencies exist.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.