Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries the transparency burden. It discloses the check digit validation, data source (National Tax Agency Web-API), and the optional history inclusion, which implies a read-only external lookup. However, it does not specify error handling, authentication requirements, or the exact return structure.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.