Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the disclosure burden. It states that the response contains values only, that polygons must come from another tool, and lists the metrics included. It could add response-size or time-period caveats, but it is transparent about the main behavioral boundary.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.