Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the burden and does well: it discloses per-call cost ($0.01 USDC on Base via x402), that payment settles before execution, that a DSSE-signed receipt is returned, and required client spend-limit setup. It even flags that funded payment/delivery through x402-proxy is unverified, which is unusually honest. It doesn't describe the response payload structure, keeping it just below a 5.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The leading question is a strong front-loaded hook, followed by the usage trigger and then payment terms. It is somewhat dense and the payment paragraph partially duplicates the schema field text, but every sentence carries operational information and none is filler.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given three simple params, full schema coverage, and no output schema, the description supplies the missing pieces an agent needs: cost, payment mechanics, prerequisite configuration, and the semantic shape of the answer (changed vs unchanged since a fingerprint). Only the concrete return payload of the DSSE receipt is left undescribed.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so all three params (url, known_fingerprint, payment_signature) are already documented. The description only restates the payment flow that the payment_signature schema field already explains, adding no format or value semantics beyond the schema. Baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Opens with a specific verb+resource: checks whether a published JSON Schema or OpenAPI document has changed since a held fingerprint. This is a distinct capability from the sibling commerce search/vet/gate tools, so an agent can route to it without opening the schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicitly frames the tool as 'the schema-drift recheck of the pre-spend policy' and says to run it 'when a provider's published contract may have moved before you pay it again,' which gives a concrete trigger condition. It stops short of naming ghost_pre_spend_gate as the alternative or saying when not to use it, but the context is clear.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.