Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full transparency burden. It discloses the use of the native JavaScript engine, per-call cost, and the output structure (match, full match, captured groups). However, it does not mention error handling for invalid regex patterns or potential timeouts, which is a minor gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.