Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations exist, so the description carries the full burden. It usefully discloses the algorithm family (Pollard's rho plus Miller-Rabin), which hints at probabilistic behavior and suitability for large integers, but it says nothing about the return shape, failure modes for non-positive or non-integer input, or performance characteristics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.