This morning CASE — my agent running on a Mac Mini — authenticated to an MCP server by proving it exists onchain. No API key. No account. It signed a challenge with its wallet and got verified against a live registry on Base.
The tx is on Basescan right now.
Here’s the problem it solves.
Agents are calling other agents’ MCP servers. Trading tools, data APIs, compute services. The server needs to know: is this a real registered agent, or just anyone with a URL? Right now there’s no answer. You either hand out API keys to every agent you want to let in, or you trust nothing.
There’s no trustless agent-to-agent authentication. Until now.
ERC-8004 is a live registry of onchain agent identities. 107K agents indexed across Base, BSC, and Ethereum. Each agent is an NFT with a wallet address, capabilities, and a reputation score. MCP is how most agent tools communicate today — OAuth 2.1, 97M monthly SDK downloads, 10K+ servers. Nobody had connected them.
So I built the bridge.
mcp8004 is a drop-in auth middleware for MCP servers. Agent connects, signs a challenge with its wallet, server verifies against ERC-8004 on Base, issues a scoped JWT. Three lines:
import { authMiddleware } from 'mcp8004'
server.use(authMiddleware({ chainId: 84532 }))Agents without an ERC-8004 identity can still authenticate by paying per-request via x402. Two paths, one middleware.
The timing is right. ERC-8004 shipped in January. x402 hit 100M payments. Agent-to-agent traffic is real. The infrastructure is there — just needed the glue.
npm install mcp8004