Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full behavioral burden. 'Basic format validation' usefully sets the expectation that deeper checks are excluded, but the description says nothing about what is returned (boolean, error, normalized address) or how invalid input is surfaced, which matters given there is no output schema.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.