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This walkthrough is the first step for the Agentic Challenge. You will use the Brickken CLI and x402 on Base Sepolia to register an ERC-8004 agent and deploy an ERC-20 owned by your wallet.
This path uses explicit client-signed execution. Your wallet signs the x402 payment and the blockchain transaction, while Brickken broadcasts the signed operation. It gives you ownership of the agent identity and token, but requires both Base Sepolia ETH for gas and Circle USDC for x402 payments.

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Outcome

At the end, your terminal will show:
  • a confirmed ERC-8004 agent registration and agentUuid;
  • the stored agent profile read back through the Agentic API;
  • a confirmed agent-owned ERC-20 deployment and tokenAddress;
  • x402 settlement metadata for the executed operations.
The complete runnable sample is in the public Agentic Hello World example.

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Estimated time

Allow 15–20 minutes for setup, faucet funding, two x402 payments, and confirmation on Base Sepolia.

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Prerequisites

1

Install the pinned CLI

Use the version validated for this programme:
2

Create a dedicated Base Sepolia wallet

Set BRICKKEN_PRIVATE_KEY and the corresponding address in WALLET. Use a testnet-only key and never commit the .env file.
3

Fund x402 payments

Get Circle USDC on Base Sepolia from the Circle faucet. The payment asset, amount, recipient, and timeout are quoted live by x402; do not hardcode them.
4

Fund transaction gas

Get Base Sepolia ETH from one of the sources in the official Base faucet list. Client-signed mode uses your wallet to pay gas.
The sample uses the public fixtures below so the registration request is runnable without inventing an image or service URL:
  • Image: https://docs.brickken.com/images/build-programme/hello-world-agent.svg
  • Service endpoint: https://docs.brickken.com/downloads/build-programme/agent-card.json

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Setup

Clone or download the example directory, then run:
The environment contract is:
Optional variables let you replace the example agent name, image, service endpoint, and token symbol.

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Run

Execute the pinned CLI workflow:

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What the script does

  1. brickken agent register prepares and executes an ERC-8004 registration on Base Sepolia with --execution-mode client-signed.
  2. The script captures agentUuid and the blockchain transaction hash, then polls the Base Sepolia RPC until the receipt succeeds.
  3. brickken agent info reads the stored profile. Without an API key, this getter uses x402 with the configured wallet.
  4. brickken create-token deploys an ERC-20 with the same wallet passed as --signer-address and --agent-wallet.
  5. The CLI waits for the deployment receipt and exposes tokenAddress; the script checks the x402 settlement and address format.
For client-controlled modes, x402 pricing is split between prepare and send. The CLI performs both payment handshakes locally and reads the live quote, so the example does not assume a fixed amount or payment token. See Agentic pricing for the execution-mode matrix.

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Expected output

The script writes JSON files under out/ and prints a summary similar to:

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Verification

Inspect the sanitized fields in out/register-output.json, out/agent-info-output.json, and out/create-token-output.json:
  • prepared.info.agentUuid exists;
  • the registration receipt has status 0x1;
  • the registration send includes successful x402 settlement metadata;
  • the profile read returns the same agent reference;
  • sent.success is true for token deployment;
  • tokenAddress is a 40-hex-character address;
  • tokenReceipt.status is 0x1 and tokenTxHash identifies the deployment receipt;
  • sent._x402.settlement.success is true.

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Troubleshooting

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Security

  • Use a disposable Base Sepolia wallet and keep the private key in an environment variable or secret manager.
  • Review the live x402 quote before approving each payment; the CLI reads the amount, asset, recipient, and timeout from the challenge.
  • Check chain, signer, agent wallet, token symbol, and recipient before executing a write.
  • Do not commit .env or the generated out/ JSON files.

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Next challenge ideas

Next, add agent set-uri and agent set-metadata, then exercise the token lifecycle with mint, approve, and transfer. For compliance-gated delegation, continue to the RAMS mandate workflow. MCP users can reach the same Agentic API through the hosted MCP server.

Agent & token workflow

See the longer CLI lifecycle walkthrough.

API Hello World

Build the direct API path for tokenized assets and STOs.