Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose the read-only nature (List) and the scope ('all'), but provides no details on return format, sorting, pagination, or access limitations. This is acceptable for a simple zero-parameter list but lacks depth.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.