{"uid":"cap_i4Avv00YuL-uSKvKbL8oQ","slug":"402-guard-x402-payment-requirement-linter-69334ad5","name":"402 Guard — x402 Payment Requirement Linter","description":"Lint x402 payment requirements or audit live DNS and email-security posture with tiny USDC payments on Base.","url":"https://x402.momentbolt.com/api/lint","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"policy":{"type":"object","description":"Optional local allowlists and caps"},"paymentRequired":{"type":"object","description":"x402 v2 PaymentRequired envelope"}}},"responseSchema":{"type":"json","example":{"ok":true,"issues":[],"summary":{"errors":0,"warnings":0,"requirementsChecked":1},"verdict":"pass","riskScore":0,"disclaimer":"This validates payment-requirement structure and caller policy; it does not establish counterparty legitimacy or provide financial advice.","policyApplied":{"allowedPayTo":["0x1111111111111111111111111111111111111111"],"maxAmountUsd":0.05,"allowedAssets":["0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913"],"allowedNetworks":["eip155:8453"],"maxTimeoutSeconds":300}}},"example":null,"exampleRequest":null,"tags":["x402"],"displayCostAmount":"0.001","displayCostAsset":"USDC","priceDynamic":false,"priceHint":null,"priceStatus":"priced","priceSource":"probe","requiresHandshake":false,"reviewCount":0,"rating":{"score":"0.00","successRate":"0.00","reviews":0,"stars":null,"state":"unrated"},"availabilityStatus":"unknown","priceObserved":null,"sessionDeposit":null,"pricing":{"kind":"static","summary":"$0.001/call","primary":{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"},"accepted":[{"kind":"static","protocol":"x402","network":"base","amountUsd":"0.001","per":"call","confidence":"exact"}]},"paymentMethods":[{"uid":"pm_WnD8So1MQT3xgwqZ6TDxG","protocol":"x402","methodType":"crypto","chain":"base","mode":"charge","costAmount":"0.001","costPer":"request","priority":0,"asset":"0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913","unit":"request","depositMicros":null,"planRef":null}],"brandName":null,"brandSlug":null,"brandBaseUrl":null,"brandDocsUrl":null,"whatItDoes":"Validates x402 v2 PaymentRequired envelopes against caller policy rules, returning a structured lint report with errors, warnings, risk score, and a pass/fail verdict.","exampleAgentPrompt":"Before my agent pays this x402 invoice, lint the PaymentRequired envelope against my policy — max $0.05 USD, pay-to must be 0x1111111111111111111111111111111111111111, USDC on Base only — and tell me if it passes or has any errors.","exampleUseCases":[{"title":"Pre-payment safety check for agent","prompt":"I'm about to let my agent pay an x402 invoice automatically — can you lint this PaymentRequired object against my policy first? My caps are max $0.05, only USDC on Base (eip155:8453), and the pay-to must be on my approved address list. Tell me the verdict and any issues before we proceed."},{"title":"Allowlist enforcement for wallet agent","prompt":"My agent received a 402 response from an external API. Validate the PaymentRequired envelope and check that the pay-to address is 0x1111111111111111111111111111111111111111 and the amount doesn't exceed $0.10 — flag any warnings or errors so I can decide whether to authorize the payment."},{"title":"Debugging malformed x402 payment header","prompt":"I'm building an x402-compatible server and my PaymentRequired envelope keeps failing client checks. Can you lint it and tell me exactly what's wrong — errors, warnings, and a risk score — so I can fix the structure?"}],"resultDescription":"A JSON object with an 'ok' boolean, an 'issues' array listing individual lint findings, a 'summary' object with error and warning counts and the number of requirements checked, a 'verdict' string ('pass' or 'fail'), a numeric 'riskScore', a 'policyApplied' object reflecting which allowlist rules were enforced, and a disclaimer about the scope of the check.","failureModes":["Malformed or missing paymentRequired object returns validation errors in the issues array","Policy fields with incompatible types may cause a 400-level rejection","Pay-to address not on allowlist returns a policy violation issue","Amount exceeding maxAmountUsd cap triggers a warning or error","Unsupported asset or network returns a disallowed-asset/network issue","Network or service unavailability returns a non-200 HTTP error"],"whenToPreferThis":"Use this endpoint when an AI agent needs to programmatically validate an x402 v2 PaymentRequired envelope before authorizing a payment — especially when enforcing caller-side policy controls like address allowlists, USD amount caps, asset restrictions, or network restrictions. Prefer this over manual inspection when operating autonomously at scale, since it returns machine-readable verdicts and risk scores. It is purpose-built for x402 payment safety and is not a general-purpose DNS or domain auditing tool.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-14T18:39:06.467Z","isFirstParty":false}