Agentic API

Overview

The Agentic API is the x402-paid surface for Brickken agentic methods. It covers ERC-8004 identity, reputation, and agent-owned ERC-20 operations on Base, plus ERC-8226 RAMS mandates on Ethereum Sepolia. Every agentic operation is a two-step flow:

Prepare the unsigned transaction. In brickken-relayed mode this is free; in client-signed and client-broadcast modes the operation charge is split between prepare and send.
Send the operation. The remaining x402 USDC charge is collected here.

There are two execution modes for the send step:

brickken-relayed (recommended). You do not sign the blockchain transaction. You pay the x402 charge and Brickken’s relayer signs, pays native gas, and broadcasts the operation on your behalf. No EOA, no native gas, no on-chain signing on your side.
client-signed. You sign the prepared blockchain transaction with your own private key and submit the signed payload. Use this when you want to retain full self-custody of signing.

Never send a private key to the Brickken API. In brickken-relayed mode you only sign the x402 payment authorization. In client-signed mode, blockchain signing belongs in your client, the Brickken CLI, or an MCP session you control.

Base URLs

Environment	Base URL
Sandbox	`https://api.sandbox.brickken.com`
Production	`https://api.brickken.com`

Networks

The Agentic API runs on Base, with Base Sepolia for tests. The x402 payment rail is operation-aligned: you pay on the same chain the operation runs on.

Network	`chainId` (decimal)	Hex	Use
Base mainnet	`8453`	`0x2105`	Production
Base Sepolia	`84532`	`0x14a34`	Testing
Ethereum Sepolia	`11155111`	`0xaa36a7`	RAMS mandates only; not ERC-8004 agent routes

Authentication Flow

For x402, omit x-api-key.

Prepare. Call a semantic facade such as POST /x402/agent/register, or POST /prepare-transactions with an eligible method. For relayed execution, pass executionMode: "brickken-relayed". The response returns txId, transactions, and an x402Requirements quote. Relayed preparation is free; client-controlled preparation may return a payment challenge for its share of the operation price.
Send. Call POST /send-transactions. The API responds 402 Payment Required with a PAYMENT-REQUIRED header describing the exact chain, asset, transfer method, amount, recipient, and timeout.
Sign the x402 payment locally with the payer’s private key, and retry the send with X-PAYMENT.
Brickken verifies the payment, then (in brickken-relayed mode) signs and broadcasts the operation. The settlement is returned in the PAYMENT-RESPONSE header.

For an agent facade, a 400 before a txId is request validation, not an insufficient x402 balance. x402 payment begins only when send-transactions returns 402 Payment Required.

X-PAYMENT: BASE64_ENCODED_X402_PAYMENT_PAYLOAD

Always read the chain, asset, transfer method, amount, recipient, and timeout from PAYMENT-REQUIRED; do not hardcode them client-side. On Base Sepolia the payment rail uses EIP-3009, whose signed authorization carries the transfer, so no separate ERC-20 approve transaction is required. On Base mainnet, follow the advertised token’s transfer method.

In brickken-relayed mode, x402 payment is mandatory — API keys are not accepted on the send step. The payment is reserved when you pay and only settled after the operation confirms on-chain. If the operation reverts or its authorization expires before confirmation, the reservation is released.

Base Sepolia Testing

Use chainId: "84532" (eip155:84532). The Base Sepolia x402 payment asset is Circle USDC:

0x036CbD53842c5426634e7929541eC2318f3dCF7e

It has 6 decimals and uses the EIP-3009 transfer method (EIP-712 name USDC, version 2, authorization window 300s). Fund the payer with the exact asset advertised by PAYMENT-REQUIRED before signing. The Base Sepolia ERC-8004 registries are:

Identity: 0x8004A818BFB912233c491871b3d84c89A494BD9e
Reputation: 0x8004B663056A597Dffe9eCcC1965A193B7388713

Discovery

GET /.well-known/x402
GET /openapi.json

Production (https://api.brickken.com) is the public x402scan target. Sandbox exposes the same discovery routes for QA.

Prepare and Send

The semantic /x402/... routes prepare unsigned transactions and do not submit transactions on-chain by themselves. Agent and token facades default to relayed execution, so their prepare is free; pass a client-controlled mode when you want to sign locally and expect the mode’s prepare charge.

Brickken-relayed (recommended)

Prepare with executionMode: "brickken-relayed" and omit signerAddress — Brickken supplies its relayer as the signer.

curl --request POST 'https://api.sandbox.brickken.com/x402/agent/register' \
  --header 'Content-Type: application/json' \
  --data '{
    "chainId": "84532",
    "executionMode": "brickken-relayed",
    "name": "Research Agent",
    "description": "Autonomous research agent",
    "image": "https://example.com/agent.png",
    "services": [
      {
        "name": "A2A",
        "endpoint": "https://agent.example/.well-known/agent-card.json",
        "version": "0.3.0"
      }
    ],
    "aiModelName": "Research Model",
    "aiModelProvider": "OpenAI",
    "x402Support": true,
    "active": true
  }'

image is required for agentRegister and must be a publicly reachable HTTPS logo URL. Do not use local paths or omit the field.

The prepare response returns a single txId, exactly one transaction { to, data, value }, and x402Requirements. Submit those to send-transactions and complete the x402 payment; Brickken signs and broadcasts:

curl --request POST 'https://api.sandbox.brickken.com/send-transactions' \
  --header 'Content-Type: application/json' \
  --header 'X-PAYMENT: BASE64_ENCODED_X402_PAYMENT_PAYLOAD' \
  --data '{
    "txId": "0xPreparedTransactionId",
    "transactions": [
      { "to": "0xRegistry", "data": "0x...", "value": "0x0" }
    ]
  }'

Client-signed

Prepare with your own signerAddress, sign the returned transaction locally, then send the signed payload:

curl --request POST 'https://api.sandbox.brickken.com/send-transactions' \
  --header 'Content-Type: application/json' \
  --header 'X-PAYMENT: BASE64_ENCODED_X402_PAYMENT_PAYLOAD' \
  --data '{
    "txId": "0xPreparedTransactionId",
    "signedTransactions": ["0xSignedRawTransaction"]
  }'

send-transactions x402 batches must contain only x402-eligible prepared transactions, and all transactions in the batch must be on the same chain. A brickken-relayed send carries a single txId and exactly one transaction.

Polling

For relayed operations, poll status with GET /get-transaction-status by txId or operation hash — no API key is required for brickken-relayed transactions. A response of status: "pending" means the operation was broadcast but not yet confirmed; do not pay or resubmit the same txId again. Brickken’s reconciliation settles after confirmation or releases the payment on revert or authorization expiry.

Endpoint Groups

Facade requests use the same body fields as the matching backend method, except method is optional and ignored because the path fixes it.

Agent Identity

Reputation

Give, revoke, and respond to ERC-8004 feedback.

Agent Tokens

Create and operate agent-owned ERC-20 tokens.

RAMS Mandates

Delegate compliance-gated, scoped, capped authority to AI-agent wallets with ERC-8226.

Pricing

Review execution-mode-aware prepare and send prices.

Advanced clients can also call POST /prepare-transactions directly and pass method explicitly. newTokenizedAgent remains a legacy alias for agent registration, but it is not published in x402scan discovery. The ten RAMS methods (ramsGrantMandate, ramsRevokeMandate, ramsExtendMandate, ramsSetOperator, ramsExecute, ramsSetExecutorAction, ramsFreezeAgent, ramsUnfreezeAgent, ramsGrantPrincipal, and ramsRevokePrincipal) are also eligible through /prepare-transactions. Their semantic facades live under /x402/rams/*.

RAMS facades default to client-signed, unlike ERC-8004 facades that inject the relayed mode by default. Only the four signature-authorized lifecycle calls may use brickken-relayed; see RAMS Mandates.

Common Fields

Field	Type	Required	Description
`chainId`	string	Yes	Target chain ID. Use `8453` for Base mainnet or `84532` for Base Sepolia. Decimal and hex values are accepted.
`method`	string	Yes for `/prepare-transactions`; no for `/x402/...` facades	One of the eligible method names. Facades derive it from the path.
`executionMode`	string	No	`brickken-relayed` (Brickken signs and broadcasts), `client-signed` (you sign, Brickken broadcasts), or `client-broadcast` (you sign and broadcast, then confirm with `txHash`). The default depends on the entry point: `/x402/agent/` and `/x402/token/` inject `brickken-relayed`; `/x402/rams/` and a direct `/prepare-transactions` call default to `client-signed` — which is a paid* prepare. See Pricing.
`signerAddress`	string	Conditional	Required in `client-signed` mode. Omit in `brickken-relayed` mode — Brickken sets its relayer as the signer.
`gasLimit`	string or number	No	Optional explicit gas limit (client-signed).
`nonce`	number	No	Optional explicit nonce when managing nonces manually (client-signed).

Response Shape

The prepare response includes txId, transactions, and optional info. For agentRegister, save info.agentUuid for later set-uri, set-metadata, and transfer-ownership calls.

x402 payments and on-chain transactions are non-refundable. Confirm chain, signer/recipient, token address, and expected USDC price before paying. See Pricing for the published mainnet table.

Overview

Agent Identity

Agent Reads

Reputation

Agent Token Operations

RAMS Mandates (ERC-8226)

RAMS Reads & Typed Data

Overview

Base URLs

Networks

Authentication Flow

Base Sepolia Testing

Discovery

Prepare and Send

Brickken-relayed (recommended)

Client-signed

Polling

Endpoint Groups

Agent Identity

Reputation

Agent Tokens

RAMS Mandates

Pricing

Common Fields

Response Shape

​Overview

​Base URLs

​Networks

​Authentication Flow

​Base Sepolia Testing

​Discovery

​Prepare and Send

​Brickken-relayed (recommended)

​Client-signed

​Polling

​Endpoint Groups

Agent Identity

Reputation

Agent Tokens

RAMS Mandates

Pricing

​Common Fields

​Response Shape

Overview

Base URLs

Networks

Authentication Flow

Base Sepolia Testing

Discovery

Prepare and Send

Brickken-relayed (recommended)

Client-signed

Polling

Endpoint Groups

Common Fields

Response Shape