Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, idempotentHint, and openWorldHint, so safety is clear. The description adds valuable context: what the response includes (rule heading, effective date, text, version history) and the authoritative source. It doesn't mention rate limits or authentication, but those are likely unnecessary for a public read-only tool.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.