Skip to main content
POST
/
x402
/
agent
/
set-metadata
Prepare ERC-8004 metadata update
curl --request POST \
  --url https://api.sandbox.brickken.com/x402/agent/set-metadata \
  --header 'Content-Type: application/json' \
  --header 'X-Payment: <api-key>' \
  --data '
{
  "chainId": "8453",
  "signerAddress": "<string>",
  "gasLimit": "<string>",
  "nonce": 123,
  "privateRpcUrl": "<string>",
  "ownerEmail": "jsmith@example.com",
  "email": "jsmith@example.com",
  "agentUuid": "<string>",
  "agentId": "<string>",
  "metadataKey": "<string>",
  "metadataValue": "<string>",
  "aiModelName": "<string>",
  "aiModelProvider": "<string>"
}
'
{
  "transactions": {},
  "txId": "<string>",
  "info": {}
}
Prepares unsigned transactions for writing an ERC-8004 agent metadata key/value pair. This facade maps to agentSetMetadata.

​
Authentication

Omit x-api-key. If the API returns 402 Payment Required, sign the x402 payment locally and retry with X-Payment.

​
Key Fields

ParameterRequiredDescription
chainIdYesTarget chain ID. Decimal and hex values are accepted.
signerAddressYesWallet that signs the prepared transaction.
agentUuid or agentIdUsuallyAgent identifier from registration or the on-chain agent ID.
metadataKeyNoMetadata key to write.
metadataValueNoMetadata value to write.
metadataEncodingNoOptional encoding descriptor for the metadata value.

​
Response

Returns prepared unsigned transactions and txId. Sign the transaction locally, then submit it with POST /send-transactions.

Authorizations

​
X-Payment
string
header
required

Base64-encoded x402 payment payload. Supported for x402-eligible agentic methods on /x402/... facades, /prepare-transactions, and eligible /send-transactions retries.

Body

application/json
​
chainId
string
default:8453
required

Target operation chain ID. Use 8453 on production Base or 11155111 on sandbox Sepolia.

Example:

"8453"

​
signerAddress
string
required

Wallet that signs the prepared blockchain transaction.

Pattern: ^0x[a-fA-F0-9]{40}$
​
gasLimit

Optional explicit gas limit.

​
nonce
number

Optional explicit nonce when managing nonces manually.

​
privateRpcUrl
string

Optional private RPC URL override.

​
ownerEmail
string<email>

Optional owner attribution email.

​
email
string<email>

Alias for ownerEmail where supported.

​
agentUuid
string

Stored tokenized agent UUID returned by agentRegister.

​
agentId
string

On-chain ERC-8004 agent ID.

​
metadataKey
string
​
metadataValue
​
metadataEncoding
enum<string>
Available options:
string,
json,
hex
​
aiModelName
string
​
aiModelProvider
string

Response

Prepared unsigned transaction payload.

​
transactions
object
​
txId
string
​
info
object