x402 Endpoint Check (Tanod)

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

Annotations already establish a safe read-only profile, but the description adds substantial behavior: nothing is paid, one unpaid request is made, it is heuristic rather than an audit, and specific error/charge semantics are given for 422, 503, and unresponsive endpoints. It also discloses timing, price, free quota, and the untrusted-data warning, all beyond the annotations without contradicting them.

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 front-loaded with purpose and alternatives, then moves through output, inputs, failure modes, cost, and safety. Every sentence earns its place by helping an agent select or correctly invoke the tool.

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 paid preflight check with an output schema, the description still supplies the operational details an agent needs: what is requested, what is charged, error behavior, expected latency, pricing, free quota, and trust boundaries. Nothing material appears missing for correct invocation.

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%, and the schema already documents both `url` and `policy`, including nested policy options. The description only restates `url` and the high-level effect of `policy`, adding little parameter-level meaning beyond the schema, so the baseline 3 is appropriate.

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?

States a specific verb and resource: checking an x402 endpoint before paying, returning pay, caution, or avoid with reasons. It explicitly distinguishes itself from x402_seller_report and benchmark_x402_price, so an agent can select it without opening sibling schemas.

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?

Gives explicit routing: use x402_seller_report for a seller checking their own listing, and benchmark_x402_price for listed prices alone. It also frames this tool as the pre-payment check, making the when-to-use condition clear.

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?

Goes well beyond the annotations: it discloses that every call settles a new on-chain payment, that failed payments are never settled and their 402 names the reason, the 1-4s latency from one on-chain settlement, the USD 0.001 price with no free tier, and where the receipt verification key lives. This is the financial-risk context the readOnlyHint=false / idempotentHint=false annotations imply but do not explain.

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?

Front-loaded with purpose and sibling routing, then cost/latency/failure semantics and a docs link. Dense but every clause carries operational value; the repeated 'agentscan:' branding prefix is the only marginal waste.

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?

An output schema exists, so return-value shape need not be spelled out, and the description still covers settlement behavior, failure modes, latency, price, and key discovery. Nothing an agent needs to decide whether and how to call this paid tool is missing.

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% and the single optional sha256 param is fully documented in the schema, including its 64-hex format. The description restates the signing semantics (hash signed with time as existence proof) without adding format or constraint detail beyond the schema, so the 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?

States a specific verb+resource (make a real x402 payment to test wallet/client) and immediately names the two sibling tools it is not (x402_payment_status, check_x402_endpoint_before_paying). An agent can distinguish this from every other x402 tool without opening a 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?

Explicit routing: use x402_payment_status to check a signed authorization without paying, use check_x402_endpoint_before_paying to vet a seller before paying. It also states the intended usage pattern (scheduled health ping). When-to-use and alternatives are fully covered.

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?

Annotations already declare readOnly/idempotent/non-destructive, but the description adds materially more: non-supported networks return 422, "Used also covers an authorization its signer cancelled," bad input is a 422 and not charged, latency is 1-3s, price is USD 0.002, and there is a free quota of 10 reads/IP/day. It also warns to treat returned text as untrusted data.

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?

Front-loaded with the purpose and alternative before dense operational facts (error codes, timing, pricing, quota, security note). Every sentence earns its place, though the middle section is clause-heavy and could be split for readability.

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 an output schema exists, return values need not be described. The description still covers network restrictions, error behavior, pricing/quota, latency, input selection, and a security caveat, leaving nothing an agent needs to invoke it correctly.

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 coverage is 100%, so baseline is 3, but the description adds the key constraint the schema does not encode: network plus either x_payment or authorizer with nonce (and optional token). That XOR-style requirement is genuine semantic value beyond the schema, which only marks network required.

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?

States a specific verb and resource with scope: "Check an x402 payment: was its USDC authorization used, can it still settle." It explicitly distinguishes itself from the sibling test_x402_payment, so an agent can route correctly without reading schemas.

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?

Names the alternative explicitly ("To make a real test payment instead use test_x402_payment") and gives the selecting condition. It also specifies when the tool applies (base/polygon/arbitrum only) and what input shapes are acceptable.

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