Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description contributes something the annotations do not: it enumerates the returned fields (parks, time zone, aliases), which is valuable precisely because no output schema exists. It says nothing about behavior for an unknown or ambiguous resort key, which is the remaining gap.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.