Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the safety profile (readOnly, idempotent, non-destructive). The description adds valuable behavioral context: the scoring formula, the output contents (total, percentile band), and a mandatory instruction to display the calculator_url as a clickable link. It does not address rounding or edge cases, so not a full 5.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.