Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral disclosure burden. 'Most things do nothing' is a useful expectation-setting detail: it tells the agent that many targets are no-ops. However, it does not describe what happens when a target does respond, what the return value looks like, or whether the action has any irreversible consequences.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.