Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the bar is lower. The description adds real behavioral value: it discloses the clamping behavior (0-100%), that the result contains a page verdict and a calculator_url, and imposes an important post-processing requirement to render that URL as a clickable markdown link.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.