Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already indicate a safe read-only, idempotent operation. The description adds valuable context by explaining the source of scores (verified outcomes vs. static estimates), what is shown (verification rates, sample counts, rankings), and requiring authentication. This goes beyond the structured fields without contradicting them.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.