Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It does disclose an important non-obvious behavior: the payment/licensing workflow (first call with empty payment_proof returns payment info, then retry with proof, or use license_key). However it omits other traits an agent needs, such as whether the operation is read-only, whether submitted data is stored, and any rate or size limits.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.