Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden. It discloses that the operation sets a mode (write) and that a restart may be required, which is a key behavioral side effect. It does not cover prerequisites or effects on current operations, but for a simple setter, this is adequate.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.