Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With zero annotations, the description carries the full burden, and it does disclose one behavioral trait: the response contains a complete prompt, a usage guide, and edge-case handling, which tells the agent the payload is a packaged prompt rather than generated content. However, it says nothing about whether the tool has side effects, how large the returned pack is, or how the optional query changes the result.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.