Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is clear. The description adds valuable behavioral detail: the decision is deterministic, policy-aware, and treats workspace paths outside the root as higher risk. It also explicitly states that arguments are 'analyzed as data and never executed', which is not present in annotations.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.