# Agent402 UK — EIP-712 Typed Data Hash

> Agent402 UK — EIP-712 Typed Data Hash is a paid API for AI agents from agent402.co.uk, paid per call via x402, $0.001/call, status down (last checked 2026-09-15).

Computes the canonical EIP-712 typed data hash for a given domain, types, and message without consuming LLM tokens

## Facts

- Endpoint: POST https://agent402.co.uk/v1/chain/eip712-hash
- Price: $0.001/call
- Payment: x402
- Status: down
- Last checked: 2026-09-15
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/agent402-uk-eip-712-typed-data-hash-5939dc83
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_RZ-Rxu8q-WyPF9CvKBqbz

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability agent402-uk-eip-712-typed-data-hash-5939dc83 -d '<json body>'
```

Example prompt: 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'}.

## When to prefer this

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.

## Known failure modes

- 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

## How this service works

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.

## Output

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.

## Request schema (JSON Schema)

```json
{
 "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"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{
 "type": "json",
 "example": {
  "hash": "0xbe609aee343fb3c4b28e1df9e632fca64fcfaede20f02e86244efddf30957bd2",
  "valid": true
 }
}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/agent402-uk-eip-712-typed-data-hash-5939dc83/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from agent402.co.uk](https://www.zero.xyz/host/agent402.co.uk/llms.txt)