x402-snap

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

No annotations are provided, so the description carries the transparency burden. It adds a behavioral trait by stating 'Free, no payment required' and 'currently available', indicating a live, no-cost read operation. However, it does not disclose return format, ordering, or error behavior, though for a zero-parameter list tool this is partially acceptable.

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 clear sentence plus a short benefit clause. It spends no words on redundancy; 'currently available' and 'Free, no payment required' both add useful meaning. Front-loading the main action makes it immediately scannable.

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 parameter-free read-only list tool, the description covers its purpose and adds cost context. It could be slightly more complete by explicitly connecting the categories to rank_x402_services, but the sibling-list context helps the agent infer that. Overall it is sufficient for such a simple tool.

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 has zero properties, so there are no parameters to document. Per the zero-parameter baseline, the description is not expected to add parameter semantics. It does not repeat any schema information and is appropriately silent on parameters.

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 'List' and identifies the exact resource ('x402 service ranking categories') with a scope qualifier ('currently available'). This clearly distinguishes it from sibling tools like rank_x402_services (which ranks) and render_url (which renders URLs).

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?

There is no explicit guidance on when to use this tool versus its siblings. The phrase 'Free, no payment required' adds cost context but does not explain when to call this before ranking or when not to use other tools. Usage is only implied by the tool's name and resource.

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.