Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=true, so the read-only safety profile is covered by structured data. The description adds a genuine behavioral detail – that the response includes the contributing factors, not just the number – but it does not disclose return format, score range, or derivation. Given annotation coverage, 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.