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

With no annotations provided, the description carries the full behavioral disclosure burden, and it does a solid job: it discloses a $1.00/call cost, a real probe purchase condition, a 'frozen disclosed precedence' for picking one blocker, and a signed verdict output. It does not detail error behavior or authentication requirements, but the most consequential side effects and costs are surfaced.

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 description is information-dense and front-loaded with the paid-call caveat, but it is structured as one long run-on sentence with parentheticals and embedded lists. Every clause contributes useful details, yet the structure is difficult to parse quickly and could benefit from clearer separation of inputs, behaviors, and outputs.

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?

For a complex tool with no output schema and no annotations, the description covers a lot: the diagnosis scope, the four data categories, the special real-purchase condition, the single-blocker output rule, and the signed verdict. It does not define the verdict's exact structure, but the essential information needed to understand what the tool does and returns is present.

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 the schema already documents all three parameters, including endpoint, expected_payto, and asserted_price_micro. The description adds useful context about 'price basis vs the category median' and the real conformance flow, but it does not materially extend the meaning of the parameters beyond what the schema already states. This is the baseline score for high schema coverage.

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?

The description clearly states that this is a 'seller-side funnel diagnosis for one x402 endpoint' and specifies the outputs: findability, conformance, category demand, competition, and one primary blocker. It is a specific verb-plus-resource statement with concrete scope, and it does not merely restate the tool name. It does not explicitly contrast itself with sibling tools like check or discover, so it misses the top score for sibling differentiation.

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?

The description gives no explicit guidance on when to choose diagnose over siblings like check, discover, register, or verify. Although it implies usage for seller-side endpoint diagnosis and references 'check's real flow', there are no stated conditions, prerequisites, or exclusions. The agent must infer the appropriate context from the name and the diagnostic framing.

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