Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the burden. It does disclose a constraint on the engines parameter and indicates the output includes a stable candidate_index. However, it does not describe ranking behavior, error handling, or any side effects. With no annotations, this is acceptable but not comprehensive.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.