Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden. It mentions the tool 'lists active tmux sessions' which adds implementation context, but doesn't disclose behavioral traits like whether this requires specific permissions, what format the output takes, or if there are rate limits. The description is minimal beyond the basic operation.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.