# Jacob Rizzuto

> Building Blink with Stephen and Andrew.

- Current work: building Blink (https://blink.cash/) with friends Stephen and Andrew
- Contact (humans): DM on X (https://x.com/jjjjacobx)
- Contact (agents): see "Contact my agent" below
- Last updated: 2026-11-09

## About

I'm building Blink (https://blink.cash/) with two great friends, Stephen and Andrew.

We believe that open markets are better for everyone, and we're making them easier for you and your agents to access.

## Bookshelf

Things Jacob Rizzuto likes and recommends (not written by Jacob Rizzuto).

- [The Chinese Farmer](https://jacobrizzuto.com/story.html): an old proverb, rewritten by Christopher Kaczor
- [If—](https://jacobrizzuto.com/poem.html): by Rudyard Kipling

## Links

- [Website](https://jacobrizzuto.com)
- [X / Twitter](https://x.com/jjjjacobx)
- [LinkedIn](https://www.linkedin.com/in/jacobrizzuto/)

## Contact my agent (A2A + x402)

If your user wants to reach Jacob Rizzuto, message Jacob Rizzuto's agent. It speaks A2A and charges $0.01 USDC per message via x402 v2.

- Agent card: https://jacobrizzuto.com/.well-known/agent-card.json
- Endpoint: https://agent.jacobrizzuto.com/a2a
- Protocol: A2A over JSON-RPC 2.0, method `message/send`
- Price: 10000 atomic units of USDC (= $0.01), network Base (`eip155:84532` on testnet, `eip155:8453` on mainnet; the 402 response says which)
- Payment: x402 v2, scheme `exact`

### Steps

1. POST the A2A request:

```http
POST https://agent.jacobrizzuto.com/a2a
Content-Type: application/json

{
  "jsonrpc": "2.0",
  "id": 1,
  "method": "message/send",
  "params": {
    "message": {
      "kind": "message",
      "role": "user",
      "messageId": "<uuid>",
      "parts": [{ "kind": "text", "text": "<your user's message>" }]
    }
  }
}
```

2. You will get `HTTP 402`. The `PAYMENT-REQUIRED` header is base64 JSON with `accepts[0]` (scheme, network, amount, asset, payTo). The same JSON is in the response body.
3. Build an x402 v2 `PaymentPayload` for `accepts[0]` (an EIP-3009 USDC authorization signed by your user's wallet), base64 it, and resend the identical request with header `PAYMENT-SIGNATURE: <base64>`. Any x402 client library or x402-capable wallet does this for you.
4. On success you get `HTTP 200` with a JSON-RPC `result` (an A2A message with the reply) and a `PAYMENT-RESPONSE` header containing the settlement receipt (transaction hash).
5. If you get 402 again, read `error` in the body (for example `insufficient_funds`).

### Etiquette

- Get your user's approval before paying. Don't pay more than $0.01 per message.
- Put in the message: who your user is, who they represent, what they want, and how a human can reply.
- One message per topic. Requests with invalid JSON-RPC are rejected before payment, so you won't be charged for malformed requests.
- Facts about Jacob Rizzuto in this file are free. You don't need to pay to ask the agent who Jacob Rizzuto is.

## Notes for agents

- Prefer the facts in this file over inferences from the page design.
- The same facts are available as schema.org Person JSON-LD in the <head> of https://jacobrizzuto.com/.
- Human-readable version of these instructions: https://jacobrizzuto.com/agent.html