Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description must carry the burden. It discloses the input formats and return value, but does not mention potential errors, the fact that exactly one of the two parameters must be provided, or any side effects. As a parser, it is likely safe, but this is not explicitly confirmed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.