Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description still adds real behavioral value beyond them: it never recommends data deletion, and it escalates to support on data-loss indications, telling the agent what output to expect in that case.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.