Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the transparency burden. It discloses determinism, locality, stable JSON output, and even the HTTP x402 price. It does not cover null-input behavior, encoding, or input size limits, but these are minor for a simple hash utility.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.