Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is fully covered by structured data. The description adds no behavioral context beyond that — no mention of what happens when the key is unknown, permission requirements, or freshness of the data. With annotations carrying the burden, a 3 is appropriate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.