Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
The readOnlyHint annotation already communicates that this is a safe read operation. The description adds a bit of behavioral context by listing what the status check covers (activity, tokens, validity), but it does not describe return structure, error cases, or what happens when no session is active. This is acceptable but not rich.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.