Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already cover the read-only/idempotent safety profile, so the description focuses on semantics an agent cannot get from structured fields: resorts with no report are excluded, zero inches counts as a real measurement, each row carries a stored Snow Score, and the two sources differ (station-measured at station elevation vs model estimate for resorts lacking a station). That is exactly the kind of behavioral context that prevents misreading results.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.