Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Description adds mapping and translation behavior beyond annotations (readOnlyHint, idempotentHint). It does not contradict annotations. However, it could include more detail on rate limits or authentication scope, though schema covers the API key requirement.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.