x402-snap

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

No annotations are provided, so the description must disclose side effects or read-only behavior. It only says 'list' which implies read-only, but it does not explicitly confirm no side effects, rate limits, or authentication requirements.

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 a single concise sentence that front-loads the action and resource. It includes a relevant note about being free without unnecessary detail.

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?

With no output schema, the description should clarify what the response contains. It states 'ranking categories' but does not specify the format (e.g., list of strings, objects) or whether it includes metadata. This leaves some ambiguity for the agent.

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?

The tool has no parameters, so there is nothing to explain. The baseline for zero parameters is 4, and the description does not need to add param details because none exist.

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 the tool lists available x402 service ranking categories, using a specific verb and resource. It is distinct from sibling tools like rank_x402_services, which perform ranking rather than listing categories.

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 hints at usage by noting it is free and returns currently available categories, implying it should be used to discover valid categories before ranking. However, it does not explicitly state when to prefer this tool over rank_x402_services or other siblings.

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

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

With no annotations, the description carries the burden of disclosing behavioral traits. It transparently states the cost ($0.02 per call in USDC on Base), the payment challenge flow, the live feed source, and the scoring factors (price, usage volume, recency). It lacks details on response format or error handling, but for a paid tool this is a solid disclosure.

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 two sentences, front-loaded with the core purpose and scoring criteria, then giving the usage prerequisite and payment mechanics. Every sentence earns its place; there is no redundancy or 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 the tool's complexity (paid API, two-phase payment, dependency on category list), the description covers the essential context: what it does, how to get valid categories, cost, and payment flow. It does not describe the return structure (e.g., JSON fields), but 'ranked list' implies a list of services, and no output schema is provided. It is complete enough for an agent to start using the tool effectively.

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?

The input schema already provides 100% coverage: category is linked to list_rank_categories, and x_payment is described with the full challenge/retry flow. The description reinforces this but adds little new meaning beyond the schema. The baseline of 3 is appropriate since the schema carries the parameter documentation burden.

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 uses a specific verb phrase 'Get a ranked list' with a clear resource ('x402 pay-per-call services') and scope ('for a task category'), and distinguishes from sibling tools by explaining the ranking criteria and the live Coinbase Bazaar feed. It is immediately clear what the tool does and how it differs from list_rank_categories and render_url.

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 explicitly instructs to 'Use list_rank_categories first to see valid categories,' providing a direct alternative and prerequisite. It also explains the two-phase payment flow: call once without x_payment to receive the challenge, then complete payment and retry. This is explicit, actionable guidance for when and how to use the tool.

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

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It transparently discusses the paid nature ($0.02/call), the x402 payment flow, and the first-call challenge, which are essential for correct invocation. However, it does not mention potential error conditions, latency, or whether the output is returned as binary or base64, leaving some behavioral gaps.

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 three sentences, each serving a distinct purpose: functionality, use case, and payment details. It is tightly written with no filler or redundancy, front-loading the most important information about the tool's core function immediately.

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?

The tool has 7 parameters and no output schema or annotations. The description covers the main purpose and payment flow well, but it does not explain the semantics of the optional parameters (waitMs, fullPage, width, height) beyond their names, nor does it specify the exact return format (e.g., binary, base64, URL). Therefore, while the description is adequate for understanding what the tool does, it is not fully complete for a complex-parameter tool without structured schema details.

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 only 29% (2 of 7 parameters have descriptions), so the description must compensate. It does clarify 'format' by listing screenshot/PDF/HTML and indirectly explains 'x_payment', but it fails to describe width, height, waitMs, and fullPage. These parameters are left to self-evident names; the description adds no extra meaning for them, and with low coverage, this is a significant shortfall.

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 the tool renders public URLs in a headless browser and returns a screenshot, PDF, or HTML. It identifies the specific resource (URL) and the action (rendering), and even names the output formats, making it unambiguous and distinct from any sibling tools.

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 provides a concrete use case: it solves the empty-shell problem when plain HTTP fetches hit client-rendered pages. This explicitly tells the agent when to use this tool instead of relying on basic fetches, and the mention of 'public URL' sets a clear prerequisite. It also implies the alternative (plain HTTP) and the scenario where this tool is superior.

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