Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
readOnlyHint=true already tells the agent this is a safe read with no side effects, and the description adds nothing on top of that — no note on whether the list is combined black/white, which direction the entries apply to, or whether the result is paginated. For a tool whose only structured signal is one annotation, the description carries almost no extra behavioral weight.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.