Agentic Methods with x402

Agentic methods are ERC-8004 and agent-token operations exposed through the standard transaction flow:

Call POST /prepare-transactions.
Sign the returned transaction locally.
Call POST /send-transactions.
Poll GET /get-transaction-status.

Private keys never leave the client. These methods can be authenticated with either an x-api-key header or an x402 payment. Non-agentic methods still require x-api-key.

x402 Authentication

For x402, omit x-api-key and call the same endpoint. If payment is required, the API returns 402 Payment Required with a PAYMENT-REQUIRED response header containing a base64-encoded x402 payment request. The client signs the x402 payment locally and retries the request with one of these headers:

X-Payment: BASE64_ENCODED_X402_PAYMENT_PAYLOAD

or:

payment-signature: BASE64_ENCODED_X402_PAYMENT_PAYLOAD

When settlement succeeds, the API includes a PAYMENT-RESPONSE header. The payment rail uses USDC with EIP-3009 authorization. The exact price, payment chain, asset, and recipient must be read from PAYMENT-REQUIRED; do not hardcode them client-side.

Eligible Methods

Method	Purpose
`newTokenizedAgent`	Legacy alias for agent registration
`agentRegister`	Register an ERC-8004 agent
`agentSetURI`	Publish the final agent URI and registration metadata
`agentSetMetadata`	Write one metadata key/value pair on-chain
`agentSetWallet`	Set the operational wallet for the agent
`agentGiveFeedback`	Submit reputation feedback
`agentRevokeFeedback`	Revoke a feedback entry
`agentAppendFeedbackResponse`	Append a response to a feedback thread
`agentCreateToken`	Deploy an ERC-20 token for the agent
`agentMintToken`	Mint an agent token
`agentBurnToken`	Burn an agent token

Common Prepare Request

All methods are prepared through POST /prepare-transactions.

curl --request POST 'https://api.sandbox.brickken.com/prepare-transactions' \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: YOUR_API_KEY' \
  --data '{
    "chainId": "11155111",
    "method": "agentRegister",
    "signerAddress": "0xYourWallet"
  }'

For x402, use the same JSON body but omit x-api-key. If the first response is 402, retry with X-Payment. Common fields:

Field	Type	Required	Description
`chainId`	string	Yes	Target chain ID. Decimal and hex values are accepted
`method`	string	Yes	One of the eligible method names
`signerAddress`	string	Yes	Wallet that signs the prepared blockchain transaction
`gasLimit`	string or number	No	Optional explicit gas limit
`nonce`	number	No	Optional explicit nonce when managing nonces manually
`privateRpcUrl`	string	No	Optional RPC override

Prepare response shape:

{
  "transactions": [
    {
      "from": "0x...",
      "to": "0x...",
      "data": "0x...",
      "nonce": 42,
      "chainId": 11155111,
      "type": 2
    }
  ],
  "txId": "0xabc123...",
  "info": {}
}

transactions can be either an object or an array depending on the method. Normalize it before signing.

Send with x402

Use POST /send-transactions after signing the prepared transaction.

curl --request POST 'https://api.sandbox.brickken.com/send-transactions' \
  --header 'Content-Type: application/json' \
  --header 'x-api-key: YOUR_API_KEY' \
  --data '{
    "txId": "0xabc123...",
    "signedTransactions": ["0xSignedRawTransaction"]
  }'

For x402, omit x-api-key and follow the same PAYMENT-REQUIRED -> X-Payment retry flow. send-transactions x402 batches must contain only x402-eligible prepared transactions, and all transactions in the batch must be on the same chain.

agentRegister

Registers a new AI agent on the ERC-8004 Identity Registry. It uploads a draft registration file to IPFS, stores a draft TokenizedAgent record, and prepares an on-chain register() transaction. Required fields:

Field	Type	Description
`method`	string	Must be `agentRegister`
`ownerEmail`	string	Email of the tokenizer account that owns the agent
`signerAddress`	string	Tokenizer wallet address
`name`	string	Agent display name
`description`	string	Agent description
`image`	string	Agent image URL or IPFS URI
`services`	array	Non-empty service descriptors

Optional fields:

Field	Type	Description
`supportedTrust`	string[]	Trust capabilities declared by the agent
`x402Support`	boolean	Whether the agent itself supports x402 payments
`active`	boolean	Agent active status. Defaults to `true`
`metadata`	object	Arbitrary metadata stored in the registration file
`aiModelName`	string	Stored under `metadata.ai.modelName`
`aiModelProvider`	string	Stored under `metadata.ai.provider`
`tags`	string[]	Discovery tags
`version`	string	Agent version
`documentation`	string	Documentation URL
`sourceCode`	string	Source code URL
`license`	string	License identifier
`agentType`	string	Agent type category
`registrations`	array	Additional registry registrations

Example:

{
  "chainId": "11155111",
  "method": "agentRegister",
  "ownerEmail": "owner@example.com",
  "signerAddress": "0xYourWallet",
  "name": "Research Agent",
  "description": "An autonomous research agent",
  "image": "ipfs://QmAgentImage",
  "services": [
    {
      "name": "A2A",
      "endpoint": "https://agent.example/.well-known/agent-card.json",
      "version": "0.3.0"
    }
  ],
  "aiModelName": "gpt-4o",
  "aiModelProvider": "openai",
  "x402Support": true,
  "active": true
}

The prepare response includes info.agentUuid. Save it for later mutation calls. newTokenizedAgent is a legacy alias that uses the same request body as agentRegister.

agentSetURI

Updates the agent’s on-chain agentURI after the registration transaction has been mined. It rebuilds the registration file, injects the real on-chain agentId, uploads the final file to IPFS, and prepares setAgentURI(agentId, newURI). Required fields:

Field	Type	Description
`method`	string	Must be `agentSetURI`
`signerAddress`	string	Must match the stored owner wallet
`agentUuid` or `agentId`	string	Stored agent reference

Optional profile override fields include name, description, image, services, metadata, aiModelName, aiModelProvider, tags, version, documentation, sourceCode, license, agentType, supportedTrust, x402Support, active, and registrations. Example:

{
  "chainId": "11155111",
  "method": "agentSetURI",
  "signerAddress": "0xOwnerWallet",
  "agentUuid": "YOUR_AGENT_UUID"
}

agentSetMetadata

Writes a single key/value pair to the ERC-8004 metadata store by preparing setMetadata(agentId, key, encodedValue). Required fields:

Field	Type	Description
`method`	string	Must be `agentSetMetadata`
`signerAddress`	string	Must match the stored owner wallet
`agentUuid` or `agentId`	string	Stored agent reference
`metadataKey` or `aiModelName`	string	Metadata key, or shorthand for `modelName`

Optional fields:

Field	Type	Description
`metadataValue`	any	Raw value to encode. If omitted, `aiModelName` is used
`metadataEncoding`	string	`string` by default, or `json` / `hex`
`aiModelProvider`	string	Stored in local profile context

Example:

{
  "chainId": "11155111",
  "method": "agentSetMetadata",
  "signerAddress": "0xOwnerWallet",
  "agentUuid": "YOUR_AGENT_UUID",
  "metadataKey": "modelName",
  "metadataValue": "gpt-4o"
}

agentSetWallet

Sets the agent’s operational wallet in the ERC-8004 Identity Registry. The new wallet must sign an authorization before the owner submits the update. Required fields:

Field	Type	Description
`method`	string	Must be `agentSetWallet`
`signerAddress`	string	Must match the stored owner wallet
`agentUuid` or `agentId`	string	Stored agent reference
`newWallet`	string	Wallet to assign as agent wallet
`signature`	string	Hex signature from the new wallet
`deadline`	number	Unix timestamp deadline for the signature

Example:

{
  "chainId": "11155111",
  "method": "agentSetWallet",
  "signerAddress": "0xOwnerWallet",
  "agentUuid": "YOUR_AGENT_UUID",
  "newWallet": "0xNewAgentWallet",
  "signature": "0xSignatureFromNewWallet",
  "deadline": 1800000000
}

agentGiveFeedback

Writes a feedback entry to the ERC-8004 Reputation Registry. Required fields:

Field	Type	Description
`method`	string	Must be `agentGiveFeedback`
`signerAddress`	string	Reviewer wallet
`agentUuid` or `agentId`	string	Target agent
`value`	string or number	Feedback value
`valueDecimals`	string or number	Decimals used to interpret `value`

Conditionally required:

Field	Description
`email`	Required when the API cannot infer tracking context from `agentUuid`

Optional fields are tag1, tag2, endpoint, feedbackURI, and feedbackHash. feedbackHash defaults to the zero hash when omitted. Example:

{
  "chainId": "11155111",
  "method": "agentGiveFeedback",
  "signerAddress": "0xReviewerWallet",
  "agentId": "7",
  "email": "reviewer@example.com",
  "value": "9500",
  "valueDecimals": 2,
  "tag1": "quality",
  "endpoint": "https://agent.example/.well-known/agent-card.json"
}

agentRevokeFeedback

Revokes a previously submitted feedback entry. Required fields:

Field	Type	Description
`method`	string	Must be `agentRevokeFeedback`
`signerAddress`	string	Original reviewer wallet
`agentId`	string or number	Target agent ID
`feedbackIndex`	string or number	Feedback index to revoke
`email`	string	Email for local tracking

Example:

{
  "chainId": "11155111",
  "method": "agentRevokeFeedback",
  "signerAddress": "0xReviewerWallet",
  "agentId": "7",
  "feedbackIndex": 0,
  "email": "reviewer@example.com"
}

agentAppendFeedbackResponse

Appends a response to an existing feedback thread. Required fields:

Field	Type	Description
`method`	string	Must be `agentAppendFeedbackResponse`
`signerAddress`	string	Agent owner wallet
`agentId`	string or number	Target agent ID
`clientAddress`	string	Reviewer wallet tied to the feedback
`feedbackIndex`	string or number	Feedback index to update
`responseURI`	string	URI of the off-chain response payload
`email`	string	Email for local tracking

Optional field: responseHash, a 32-byte content hash. It defaults to the zero hash when omitted. Example:

{
  "chainId": "11155111",
  "method": "agentAppendFeedbackResponse",
  "signerAddress": "0xOwnerWallet",
  "agentId": "7",
  "clientAddress": "0xReviewerWallet",
  "feedbackIndex": 0,
  "responseURI": "ipfs://QmResponseCID",
  "email": "owner@example.com"
}

agentCreateToken

Deploys a new ERC-20 token for the agent through the Agent Token Factory. Required fields:

Field	Type	Description
`method`	string	Must be `agentCreateToken`
`ownerEmail` or `email`	string	Tokenizer email
`signerAddress`	string	Wallet that signs and pays gas
`name`	string	Token name
`symbol`	string	Token ticker, 2-11 uppercase alphanumeric characters
`agentWallet`	string	Agent wallet that will own the token

Optional fields:

Field	Type	Description
`premint`	string	Human-readable amount minted to `agentWallet`. Defaults to `0`
`decimals`	number	Token decimals, 0-255. Defaults to `18`

Example:

{
  "chainId": "11155111",
  "method": "agentCreateToken",
  "ownerEmail": "owner@example.com",
  "signerAddress": "0xOwnerWallet",
  "name": "My Agent Token",
  "symbol": "MAT",
  "agentWallet": "0xAgentOperationalWallet",
  "premint": "1000000",
  "decimals": 18
}

After send-transactions succeeds, read the deployed tokenAddress from the send result.

agentMintToken

Mints additional tokens by calling mint(to, amount) on the deployed agent token. Required fields:

Field	Type	Description
`method`	string	Must be `agentMintToken`
`ownerEmail` or `email`	string	Tokenizer email
`signerAddress`	string	Must be the configured `agentWallet`
`tokenAddress`	string	Deployed ERC-20 token address
`to`	string	Recipient wallet
`amount`	string	Human-readable amount to mint

Optional field: decimals, defaulting to 18. Example:

{
  "chainId": "11155111",
  "method": "agentMintToken",
  "ownerEmail": "owner@example.com",
  "signerAddress": "0xAgentOperationalWallet",
  "tokenAddress": "0xDeployedTokenAddress",
  "to": "0xRecipientAddress",
  "amount": "500",
  "decimals": 18
}

agentBurnToken

Burns tokens by calling burn(from, amount) on the deployed agent token. Required fields:

Field	Type	Description
`method`	string	Must be `agentBurnToken`
`ownerEmail` or `email`	string	Tokenizer email
`signerAddress`	string	Must be the configured `agentWallet`
`tokenAddress`	string	Deployed ERC-20 token address
`from`	string	Address to burn from
`amount`	string	Human-readable amount to burn

Optional field: decimals, defaulting to 18. Example:

{
  "chainId": "11155111",
  "method": "agentBurnToken",
  "ownerEmail": "owner@example.com",
  "signerAddress": "0xAgentOperationalWallet",
  "tokenAddress": "0xDeployedTokenAddress",
  "from": "0xAddressToBurnFrom",
  "amount": "100",
  "decimals": 18
}

Nonce Ordering

For multi-step agent workflows, wait for each transaction to be mined before preparing the next one. Preparing multiple dependent agent transactions before the first one is mined can produce nonce conflicts. The canonical profile flow is:

agentRegister
Wait for the registration transaction to be mined and processed.
agentSetURI
Wait for the URI transaction to be mined and processed.
agentSetMetadata

API Documentation

Create Transaction

Send Transaction

Agentic Methods (x402)

On Behalf Endpoints

Information Endpoints

Management Endpoints

x402 Authentication

Eligible Methods

Common Prepare Request

Send with x402

agentRegister

agentSetURI

agentSetMetadata

agentSetWallet

agentGiveFeedback

agentRevokeFeedback

agentAppendFeedbackResponse

agentCreateToken

agentMintToken

agentBurnToken

Nonce Ordering

API Documentation

Create Transaction

Send Transaction

Agentic Methods (x402)

On Behalf Endpoints

Information Endpoints

Management Endpoints

Documentation Index

​x402 Authentication

​Eligible Methods

​Common Prepare Request

​Send with x402

​agentRegister

​agentSetURI

​agentSetMetadata

​agentSetWallet

​agentGiveFeedback

​agentRevokeFeedback

​agentAppendFeedbackResponse

​agentCreateToken

​agentMintToken

​agentBurnToken

​Nonce Ordering

x402 Authentication

Eligible Methods

Common Prepare Request

Send with x402

agentRegister

agentSetURI

agentSetMetadata

agentSetWallet

agentGiveFeedback

agentRevokeFeedback

agentAppendFeedbackResponse

agentCreateToken

agentMintToken

agentBurnToken

Nonce Ordering