Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes far beyond the sparse annotations. It discloses that English terms and numbers pass through unchanged, explains the verification semantics ('verified: true' vs fallback to unchanged input), states the 10,000 character limit, and notes the monthly quota. This is rich, non-obvious behavioral context that an agent needs to interpret results correctly.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.