Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Goes well beyond the readOnlyHint/openWorldHint annotations: it declares the tool is free and charges nothing, is idempotent, that an unknown id produces an HTTP 404 error, and the external data source. That is exactly the kind of cost and failure-mode context an agent needs before calling.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.