Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description carries the full burden — and it does add value by stating the returned fields (file path, mod ID, format, size), which tells a caller what to expect. Still, the description doesn't disclose anything about recursion depth, error behavior on bad directories, sorting, or whether this is a pure read (obvious for 'list' but not stated). Adding return-field semantics is useful, but the missing behavioral detail and absence of any mention of file count limits or permission requirements keeps it at the baseline.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.