{"uid":"cap_RZ-Rxu8q-WyPF9CvKBqbz","slug":"agent402-uk-eip-712-typed-data-hash-5939dc83","name":"Agent402 UK — EIP-712 Typed Data Hash","description":"Don't burn tokens on deterministic work. Go/no-go jobs first: payout preflight, text firewall (PII/secrets), budget check — then rails, calendars, finmath. x402 USDC on Base. UK + global. agent402.co.uk — not agent402.tools. $0.001–$0.002 USDC on Base. No API keys.","url":"https://agent402.co.uk/v1/chain/eip712-hash","method":"POST","headers":{},"bodySchema":{"type":"object","properties":{"types":{"type":"object","description":"Primary + referenced types (EIP712Domain optional)"},"domain":{"type":"object","description":"EIP-712 domain"},"message":{"type":"object","description":"Message matching primaryType"},"typedData":{"type":"object","description":"Optional envelope {domain,types,primaryType,message}"},"primaryType":{"type":"string","description":"Root type name"}}},"responseSchema":{"type":"json","example":{"hash":"0xbe609aee343fb3c4b28e1df9e632fca64fcfaede20f02e86244efddf30957bd2","valid":true}},"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":"down","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_YARzYXnBU0rgL1GrtkdK8","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":"Computes the canonical EIP-712 typed data hash for a given domain, types, and message without consuming LLM tokens","exampleAgentPrompt":"Compute the EIP-712 hash for this typed data — domain is {name:'MyApp',version:'1',chainId:8453,verifyingContract:'0xabc...'}, primaryType is 'Transfer', types include Transfer with fields {to:address,amount:uint256}, and the message is {to:'0x123...',amount:'1000000'}.","exampleUseCases":[{"title":"USDC permit hash before signing","prompt":"Hash this EIP-712 typed data for a USDC permit on Base: domain name is 'USD Coin', chainId 8453, verifyingContract is the Base USDC address, primaryType is 'Permit', and the message has owner, spender, value, nonce, and deadline fields filled in — give me the hex hash I need to sign."},{"title":"Smart contract meta-transaction signing","prompt":"I need the EIP-712 hash for a meta-transaction: domain is {name:'Forwarder',version:'1',chainId:8453}, primaryType 'ForwardRequest' with fields from, to, value, gas, nonce, and data — here's the full message object. What's the canonical hash?"},{"title":"Off-chain order hash for DEX","prompt":"Compute the EIP-712 hash for a limit order typed data: the domain is my DEX contract on Base (chainId 8453), primaryType is 'Order' with fields maker, taker, tokenIn, tokenOut, amountIn, amountOut, expiry, and nonce. Here's the full message — I need the hash to confirm it matches what the contract will compute."}],"resultDescription":"Returns a JSON object with a 'hash' field (a 0x-prefixed 32-byte hex string representing the canonical EIP-712 typed data hash) and a 'valid' boolean indicating whether the input was well-formed and the hash was successfully computed.","failureModes":["Malformed or missing 'types' object returns an error or valid:false","Missing primaryType field causes hash computation to fail","Domain fields that don't match EIP-712 spec may produce incorrect hashes without explicit error","Mismatched message fields vs declared types may result in invalid:true","Network or payment (x402) errors may return 402 Payment Required if USDC payment fails"],"whenToPreferThis":"Use this endpoint when you need a deterministic, token-free computation of an EIP-712 typed data hash — especially before signing USDC permits, meta-transactions, or any EVM structured data. Prefer this over having an LLM compute the hash inline (error-prone and expensive) or spinning up a local ethers.js/web3 environment. Ideal for agent pipelines that need to verify or pre-compute signatures on Base or other EVM chains without running code locally.","instructions":null,"reviewSummary":null,"reviewSummaryHighlights":null,"reviewSummaryConcerns":null,"reviewSummaryGeneratedAt":null,"activationCount":0,"lastUsedAt":null,"lastSuccessfullyRanAt":null,"lastHealthCheckAt":"2026-09-15T10:25:30.045Z","isFirstParty":false}