Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. It states the tool creates a new .xlsx file but does not mention whether it requires special permissions, where the file is saved, whether an existing file can be overwritten, or what the return value is. For a side-effecting tool, this leaves important behavioral traits undisclosed.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.