Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds genuine context beyond that: the tool emits a line for decisions.jsonl and, when a durable rule is stated, also produces a learning candidate with the location to persist it. Note a mild tension: 'Record' reads like a write, but 'Returns a line for decisions.jsonl' reconciles it as a read-only composition step.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.