Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, and non-destructive behavior. The description adds the key behavioral trait that unavailable benchmarks return coming_soon with null estimates rather than falling back to manual planning defaults, which is valuable beyond annotation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.