Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, open-world, non-destructive, so the safety profile is covered. The description adds the commercially critical fact that this is a paid call requiring an ENTERPRISE contract, which is real value beyond structured fields. It says nothing about not-found behavior or failure modes.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.