Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already mark the tool as read-only and idempotent, and the description adds meaningful extra context: it preserves whole sentences, reports before/after token estimates, and discloses the $0.005 USDC payment on Base via x402. This is strong behavioral transparency, though it does not cover edge-case behavior such as overly small token budgets.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.