Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (destructive, non-idempotent, open-world), so the bar is lower. The description adds real behavioral value beyond them by disclosing the structured-data eligibility restriction, which determines whether the call will succeed at all. It omits auth/quota context, keeping it from a 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.