Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It conveys that this is a read-only listing returning two distinct sets (startable workspaces and running sessions), which is useful. It omits authentication requirements, pagination, and whether results are scoped to the user.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.