Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It clearly discloses the state-flipping behavior and the full-brightness action, which is core. However, it omits details like what happens with an invalid id, whether it returns the new state, or any side effects like state persistence. For a simple tool, the disclosed behavior is reasonably transparent but not exhaustive.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.