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 disclose one genuinely useful non-obvious trait, "the canvas grows to fit," telling the agent the result bounding box expands rather than clipping. It omits other important behavior: whether negative degrees rotate counterclockwise, whether the operation is destructive to existing pixels, how new corner regions are filled, and interpolation/quality characteristics.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.