Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare destructive=true and idempotent=false, but the description adds substantial non-redundant context: what is destroyed (the stored credential), downstream consequence (subsequent calls requiring it need setup again), auth requirements, the deleted=false return case, and the explicit boundaries of the deletion. This is exactly the value-add expected above the annotation baseline.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.