Steward MCP

Steward MCP Server

Steward's x402 pay-per-call rail as MCP tools. Any MCP-compatible agent (Claude, Cursor, Windsurf, MCP-aware frameworks) gets Steward's catalog natively in its tool list — each paid call settles $0.01–$0.02 USDC on Base, signed by your own wallet.

Current release: v0.3.1 — run it with npx -y @brianbooms/steward-mcp (25 tools: 14 paid + 11 free).

Steward is the machine Brian Booms named: it quotes fair prices, verifies payment cryptographically, delivers goods, and accounts for every cent.

• Rail: https://pay.brianbooms.com · Build V3.9.203-STANDARD
• Fair Dealing (the terms): https://brianbooms.com/fair-dealing/
• Brian Booms is an AI-assisted artist and content creator.

Tools (25 total — one canonical server)

Paid calls — USDC on Base each, settled from your wallet

The three steward_audio_* lanes are live rail-side since worker V3.9.195-AUDIO. The three trust_* tools are live rail-side since worker V3.9.203-STANDARD. All trust tools are read-only and advisory — verification can never be purchased.

Read-only discovery — free, never signs or spends

Superseded servers

This is the one canonical MCP server. The directories below are left in place for history but are superseded — do not build on them:

Install

Requires Node 20+. No install step — run the published package (v0.3.1):

npx -y @brianbooms/steward-mcp

From source (this repo):

cd steward-mcp
npm install
npm run build

Configure

cp .env.example .env
# edit .env:

Your key never leaves your machine. The server uses it only to sign a per-call EIP-3009 authorization ($0.01 USDC on Base, payee verified as Steward's wallet 0xa98e8c6cbc64b7bb30fd0d2015ab24814c661839). It is never logged, stored, or transmitted anywhere else. Fund the wallet with a few USDC on Base and each tool call spends exactly what the rail quotes — nothing more.

Add to Claude Code / Cursor / Windsurf

Claude Code (~/.claude.json or project .mcp.json):

{
  "mcpServers": {
    "steward": {
      "command": "npx",
      "args": ["-y", "@brianbooms/steward-mcp"],
      "env": {
        "STEWARD_PAYER_KEY": "0x...",
        "STEWARD_MAX_SPEND_USDC": "0.05",
        "STEWARD_MAX_SPEND_DAY_USDC": "5.00"
      }
    }
  }
}

Cursor (.cursor/mcp.json): same shape under "mcpServers".

Restart the host, and the steward_* tools appear in the agent's tool list. Ready-to-paste configs for Claude Desktop, Cursor, Windsurf, Cline, and Codex: https://github.com/brianbooms/steward-examples

Framework integrations

Steward works natively with every major agent framework via MCP. No wrappers needed — point the framework's MCP client at Steward and the tools appear.

Worked examples: steward-examples (index + client configs) · LlamaIndex · CrewAI · ElizaOS plugin · eval kit

LangChain

from langchain_mcp_adapters import MultiServerMCPClient

client = MultiServerMCPClient({
    "steward": {
        "command": "npx",
        "args": ["-y", "@brianbooms/steward-mcp"],
        "env": {"STEWARD_PAYER_KEY": "0x..."},
        "transport": "stdio",
    }
})
tools = await client.get_tools()  # steward_* tools as LangChain StructuredTools

LlamaIndex

from llama_index.tools.mcp import BasicMCPClient, McpToolSpec

mcp_client = BasicMCPClient(
    command_or_url="npx",
    args=["-y", "@brianbooms/steward-mcp"],
    env={"STEWARD_PAYER_KEY": "0x..."},
)
tool_spec = McpToolSpec(client=mcp_client)
tools = tool_spec.to_tool_list()

CrewAI

from crewai_tools import MCPServerAdapter

with MCPServerAdapter(
    command="npx",
    args=["-y", "@brianbooms/steward-mcp"],
    env={"STEWARD_PAYER_KEY": "0x..."},
) as tools:
    # tools = CrewAI-compatible steward_* tools
    agent = Agent(tools=tools, ...)

AutoGen / AG2

from autogen_ext.tools.mcp import StdioServerParams, mcp_server_tools

server_params = StdioServerParams(
    command="npx",
    args=["-y", "@brianbooms/steward-mcp"],
    env={"STEWARD_PAYER_KEY": "0x..."},
)
tools = await mcp_server_tools(server_params)

Vercel AI SDK

import { createMCPClient } from "@ai-sdk/mcp";

const mcpClient = await createMCPClient({
  transport: {
    type: "stdio",
    command: "npx",
    args: ["-y", "@brianbooms/steward-mcp"],
    env: { STEWARD_PAYER_KEY: "0x..." },
  },
});

const tools = await mcpClient.tools();
// use with generateText({ model, tools, prompt })

How payment works

1. Tool calls the rail endpoint with no payment.
2. Rail answers HTTP 402 with an x402 quote (price, payee, asset, timeout).
3. The server verifies: scheme exact, network base, payee is Steward's wallet, asset is USDC on Base, price sane and within your caps.
4. It signs an EIP-3009 transferWithAuthorization with your key and resubmits with the X-PAYMENT header.
5. Rail verifies via its facilitator and returns the result as the tool output.

Anything unexpected — wrong payee, wrong asset, price over your cap — and the server refuses to sign. No silent spending, ever.

Verify without paying

npx tsx test/quotes.test.ts   # probes all 25 tools' live quotes, signs nothing
npx tsx test/smoke.test.ts    # boots the MCP server, lists tools over stdio

Trust

• Prices are quoted by the rail per call; the server never invents a price.
• Every settled call appears on steward_receipts — public, per wallet.
• The terms: https://brianbooms.com/fair-dealing/ (the Fair Dealing page controls).
• Machine-readable catalog: https://brianbooms.com/.well-known/purchase-catalog.json

License

MIT — Synthetic Universe LLC.