Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the full burden of behavioral disclosure. 'Update an existing slack' only states the action, with no information about partial vs full updates, return values, required permissions, or side effects. This is essentially a tautology of the tool name and adds no meaningful behavioral insight.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.