Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden and does so reasonably: it discloses the hard failure mode (400 below 20 values), the statistical caveat that small samples lack discriminating power, and states what it returns (p-value plus its own limitations). It doesn't cover auth or rate limits, but for a pure computation tool the key behavioral traits are surfaced.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.