Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the behavioral burden. 'Listar' signals a read-only operation and the description reveals the output contract (name, trigger, step count). It does not discuss project scope, sorting, or response format, but for a parameterless list tool this is sufficient.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.