Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full behavioral burden. "List" implicitly signals a read-only, non-destructive operation and the presence of the active tab among the results is disclosed, but there is no statement about ordering, pagination, or that this never mutates browser state. The implicit read-only semantics keep it at a minimum-viable 3 rather than lower.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.