{"uid":"cap_afhEr0vmEcTkHtYUx-AEQ","slug":"agentindex-x402-echo-310b6f82","name":"AgentIndex x402 Echo","description":"Cheapest possible Base-mainnet x402 conformance call: settle $0.001 of USDC and receive payer identity, request echo and receipt. Built for agents testing wallets, Payment-Signature, facilitators and settlement. Try GET /x402-echo/sample.","url":"https://x402.agentindex.world/x402-echo?utm_source=zero.xyz","method":"GET","headers":{},"bodySchema":{"type":"object","$schema":"https://json-schema.org/draft/2020-12/schema","required":["input"],"properties":{"input":{"type":"object","required":["type","method"],"properties":{"type":{"type":"string","const":"http"},"method":{"enum":["GET","HEAD","DELETE"],"type":"string"},"queryParams":{"type":"object","required":[],"properties":{"message":{"type":"string","description":"Optional test message to echo after successful settlement."}}}},"additionalProperties":false},"output":{"type":"object","required":["type"],"properties":{"type":{"type":"string"},"example":{"type":"object","required":["ok","purpose","network","price_usdc","price_atomic_usdc","request"],"properties":{"ok":{"type":"boolean"},"payer":{"type":["string","null"]},"network":{"type":"string"},"purpose":{"type":"string"},"request":{"type":"object"},"price_usdc":{"type":"number"},"x402_receipt":{"type":"object"},"price_atomic_usdc":{"type":"string"}}}}}}},"responseSchema":{"type":"json","example":{"ok":true,"payer":"0xb3F32bdfe8D07825BC0D7387295aB1D7559BA69d","network":"eip155:8453","purpose":"x402-mainnet-conformance","request":{"echo":{"hello":"agent"},"method":"POST"},"price_usdc":0.001,"price_atomic_usdc":"1000"}},"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_1syNL_s_GJN8gHG16UiCe","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 micropayment settlement by echoing the request back with payment confirmation details after a $0.000001 USDC payment on Base.","exampleAgentPrompt":"Send a quick test echo request to the AgentIndex x402 endpoint with message 'hello agent' to confirm my micropayment settlement is working correctly on Base mainnet.","exampleUseCases":[{"title":"Verify x402 integration before deployment","prompt":"Run an echo test against the AgentIndex x402 endpoint with message 'pre-deploy-check' so I can confirm the payment settlement and receipt flow is working before I go live."},{"title":"Debug payer address in payment receipt","prompt":"Hit the x402 echo endpoint with a GET and the message 'debug-wallet' — I need to see the payer address and x402_receipt fields that come back after settlement to verify my wallet is being recognized correctly."},{"title":"Cheapest possible mainnet payment test","prompt":"Do the cheapest possible real mainnet x402 payment test on Base using the AgentIndex echo endpoint — I just want to confirm $0.000001 USDC actually settles and returns an ok:true response."}],"resultDescription":"Returns a JSON object confirming settlement with: ok (boolean), payer wallet address, network identifier (eip155:8453 for Base), purpose string, echoed request object, price in USDC (0.000001), atomic price in USDC units, and the full x402 payment receipt.","failureModes":["Payment not settled — returns 402 if USDC micropayment is not included or fails","Invalid method — only GET, HEAD, DELETE are accepted","Malformed queryParams — unrecognized fields rejected due to additionalProperties:false","Insufficient balance — agent wallet lacks USDC on Base","Network mismatch — payment sent on wrong chain returns settlement error"],"whenToPreferThis":"Use this endpoint when you need to verify that your x402 micropayment integration is working end-to-end on Base mainnet at the absolute minimum cost ($0.000001 USDC). It is the canonical conformance test for the AgentIndex x402 protocol stack. Prefer this over other echo or health-check endpoints when you specifically need to confirm payment settlement, receipt generation, and payer address recognition in a single call.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-10-02T04:30:51.086Z","isFirstParty":false,"canonicalSlug":"agentindex-x402-echo-310b6f82"}