Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the behavioral burden. It does disclose that the output is Markdown and that filename drives format detection, which is useful. However, it does not mention constraints like size limits, invalid base64 handling, or whether any external call is involved. The description is minimally acceptable but leaves gaps.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.