Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. It does not state whether this requires a license/api_key, whether it is a pure computation or a server call, how peaks input should be formatted, or how tolerance is applied. Only the basic transformation is conveyed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.