Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so safety and scope are covered. The description adds that results are public video cards and channels, but says nothing about pagination, ordering, or behavior when slug is omitted. With annotations carrying the safety profile, 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.