Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint=true already declares the safety profile, so the description's real contribution is disclosing that each team carries its members and availability. That is useful beyond the annotations, but it says nothing about result set size, pagination behavior (despite a cursor param), or what availability means operationally.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.