Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true and openWorldHint=false, and the description complements this by disclosing the response semantics (✓ exists, ✗ missing, ⚠ ambiguous law name) and that validation is against current law. It does not cover latency, rate limits, or partial-match behavior, but adds real value beyond the annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.