Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
There are no annotations, so the description carries the burden of conveying behavior. 'List every account across every linked institution' transparently signals a global, unfiltered read operation, but it does not disclose details like pagination, performance, or authentication side effects. The output schema covers return shape.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.