SET UP THE
MCP SERVER.

How It Works

The P402 MCP server exposes six tools over the Model Context Protocol (MCP). When your AI host calls p402_chat, P402 routes the request to the cheapest capable provider, applies your session budget, and returns an OpenAI-compatible response — all transparently.

The server ships as an npm package. No global install needed — npx handles it.

P402_API_KEY=your_key npx -y @p402/mcp-server@latest

The server starts on stdio (default) or --transport sse --port 3100 for HTTP SSE mode.

Open claude_desktop_config.json and add the P402 server block. Claude Desktop auto-restarts the server on each session.

{
  "mcpServers": {
    "p402": {
      "command": "npx",
      "args": ["-y", "@p402/mcp-server@latest"],
      "env": {
        "P402_API_KEY": "your_p402_api_key_here"
      }
    }
  }
}

In Cursor: Settings → MCP → Add Server. Use the stdio transport.

{
  "mcpServers": {
    "p402": {
      "command": "npx",
      "args": ["-y", "@p402/mcp-server@latest"],
      "env": { "P402_API_KEY": "your_key" }
    }
  }
}

For programmatic access, start the server in HTTP SSE mode and connect with the official MCP TypeScript SDK.

# Terminal 1 — start the server
P402_API_KEY=your_key npx -y @p402/mcp-server@latest --transport sse --port 3100

// Terminal 2 — connect via SDK
import { Client } from '@modelcontextprotocol/sdk/client/index.js';
import { SSEClientTransport } from '@modelcontextprotocol/sdk/client/sse.js';

const client = new Client({ name: 'my-agent', version: '1.0' }, { capabilities: {} });
const transport = new SSEClientTransport(new URL('http://localhost:3100/sse'));

await client.connect(transport);

// Call p402_chat
const result = await client.callTool({
  name: 'p402_chat',
  arguments: {
    messages: [{ role: 'user', content: 'What is EIP-3009?' }],
    mode: 'cost',
    cache: true,
    session_id: 'YOUR_SESSION_ID',   // optional
  },
});

console.log(result.content[0].text);

Available Tools

Environment Variables