Attach Vital Metadata requires a canonical metadata envelope, and Attach Useful Metadata lists further context that should travel with it. The specification requires a documented format, but not any particular one. The following illustrates one way a Producer might satisfy both requirements. The field names are illustrative and carry no normative weight.
{
"envelopeVersion": "1",
"intent": {
"description": "Monthly payroll transfer to contractor",
"reference": "PAY-2026-08-0042"
},
"inputs": {
"chain": "eip155:1",
"from": "0x5B38Da6a701c568545dCfcB03FcB875f56beddC4",
"to": "0xAb8483F64d9C6d1EcF9b849Ae677dD3315835cb2",
"token": {
"address": "0xA0b86991c6218b36c1d19D4a2e9Eb0cE3606eB48",
"symbol": "USDC",
"decimals": 6
},
"amount": "1250000000",
"nonce": 42
},
"unsignedTransaction": "0x02f8b00182002a8459682f008501dcd6500082b41e94a0b869...",
"transactionHash": {
"algorithm": "keccak256",
"value": "0x9c22ff5f21f0b81b113e63f7db6da94fedef11b2119b4088b89664fb9a3cb658"
},
"context": {
"requiredSigners": [
"0x617F2E2fD72FD9D5503197092aC168c91465E7f2",
"0x17F6AD8Ef982297579C203069C1DbfFE4348c372"
],
"signerThreshold": 2,
"policyTags": ["payroll", "recurring"],
"gasPolicy": {
"maxFeePerGas": "30000000000",
"maxPriorityFeePerGas": "1500000000"
},
"expiry": "2026-08-31T23:59:59Z"
},
"producerAttestation": {
"producerId": "producer-eu-1",
"algorithm": "secp256k1",
"signature": "0x4f3c1b...",
"created": "2026-08-24T09:14:02Z"
}
}
The producerAttestation signature is what binds the envelope to the transaction, covering the serialized intent, inputs, unsignedTransaction and transactionHash fields, so that a receiving role can satisfy the requirement Verify Received Transactions without trusting the channel it arrived on.