@mailam/bruno-agentkit¶

Lets an agent built on Coinbase's AgentKit act on Ethereum while holding only USDC and no ETH. It pays Bruno, the permissionless gas relay, over x402 from its own wallet, and the payment only goes through if its transaction succeeds and lands. There's no API key and no account to set up.

Install¶

From npm, or from JSR:

npm install @mailam/bruno-agentkit    # npm
pnpm add @mailam/bruno-agentkit       # pnpm
bun add @mailam/bruno-agentkit        # Bun
deno add jsr:@mailam/bruno-agentkit   # Deno, from JSR

Its versions are prereleases (-dev) until its API settles. On JSR, for npm, pnpm and Bun: npx jsr add @mailam/bruno-agentkit, pnpm i jsr:@mailam/bruno-agentkit, bunx jsr add @mailam/bruno-agentkit.

It works wherever AgentKit does: Node 20 or later, Bun or Deno.

Use¶

import { AgentKit } from "@coinbase/agentkit";
import { brunoActionProvider } from "@mailam/bruno-agentkit";

const agentkit = await AgentKit.from({
  walletProvider, // any EVM wallet provider, on Ethereum mainnet or Sepolia
  actionProviders: [brunoActionProvider()],
});

From there, use AgentKit's framework extensions (LangChain, Vercel AI SDK, MCP) as you normally would.

Actions¶

Every action that pays takes a maxFee: the most USDC to pay Bruno, in whole units as a decimal ("5" by default). If Bruno's price is higher than that, it's refused before anything is signed.

send_call_gasless runs the call from Bruno's own contract, not from the agent's wallet. Its description tells the agent this: it's for calls whose effect doesn't depend on who sends them (a claim to a named recipient, a signed authorization, a mint for an address). Moving USDC from the wallet is what send_usdc_gasless is for.

Options¶

brunoActionProvider({
  url: "https://bruno.mailam.app", // the relay (this is the default)
  fetch, // a fetch of your own, if you need one
  chains: {
    // chains beyond Ethereum mainnet and Sepolia that your relay serves, by chain id: each with
    // its tokens, USDC among them
    "31337": [{ symbol: "USDC", address: "0x…", decimals: 6 }],
  },
});

Limits¶

• Chains: Ethereum mainnet and Sepolia, and any other chain your relay serves, given in chains.
• Wallets: any EVM wallet provider: a key (a viem or CDP key wallet), or a smart wallet (CDP's smart wallet provider, ZeroDev, or a viem smart account), deployed or not. A smart wallet that isn't deployed yet is deployed by the same transaction that takes its first payment, so it never needs ETH. Tested through AgentKit's viem wallet provider, with Coinbase Smart Wallets v1 and v1.1, and with ZeroDev's Kernel v3.2 made as ZeroDevWalletProvider makes it. That provider itself can't be run on a local chain, as it takes its chain from AgentKit's list of public networks. CDP's smart wallet provider makes Coinbase Smart Wallets v1.1, but needs CDP's servers, so it isn't tested itself.
• Telemetry: the actions send none. They're registered directly rather than through AgentKit's @CreateAction decorator, so AgentKit's per-action events aren't sent. AgentKit's wallet providers still report themselves to Coinbase when created (the wallet's address and chain), whatever actions they're given.

Links¶

• @mailam/bruno: the client this is built on, for paying for calls outside AgentKit
• Bruno
• Source

License¶

Apache-2.0. Copyright mai-lam-labs.

API reference¶

Every export, from its documentation comments: jsr.io/@mailam/bruno-agentkit/doc.