Skip to main content
Glama
botanicastudios

MCP Host RPC Bridge

MCP Host RPC Bridge

A Node.js library that bridges MCP (Model Context Protocol) tool calls to JSON-RPC function calls. Supports both Unix socket connections (default) and HTTP transport for flexible integration with any application architecture.

Features

  • 🚀 Dual Transport Modes: Unix sockets for local IPC, HTTP for web integration

  • 🔐 JWT Authentication: Secure context passing with cryptographic signatures

  • 🔧 Framework Agnostic: Works with Express, Fastify, Next.js, or raw Node.js

  • 📝 TypeScript Support: Full type definitions included

  • 🎯 Zod Integration: Automatic schema conversion for type-safe tools

Related MCP server: MCP JSON-RPC Server

Installation

npm install @botanicastudios/mcp-host-rpc

Quick Start

Socket Mode (Default)

import { McpHost } from '@botanicastudios/mcp-host-rpc/host';

// Create host with Unix socket transport (default)
const host = new McpHost({ debug: true });

// Register a tool
host.registerTool('get_data', {
  title: 'Get Data',
  description: 'Retrieves data from the system',
  functionName: 'getData',
  inputSchema: {
    type: 'object',
    properties: {
      id: { type: 'string' }
    },
    required: ['id']
  }
}, async (context, args) => {
  return { type: 'text', text: `Data for ${args.id}` };
});

// Start the server
await host.start();

// Get MCP server configuration
const config = host.getMCPServerConfig(
  'my-server',
  ['get_data'],
  { userId: '123', permissions: ['read'] }
);

HTTP Mode

import express from 'express';
import { McpHost } from '@botanicastudios/mcp-host-rpc/host';

const app = express();

// Create host with HTTP transport
const host = new McpHost({
  transport: 'http',
  httpPath: '/mcp-rpc',
  httpUrl: 'http://localhost:3000/mcp-rpc'
});

// Set up HTTP endpoint
app.use(express.json());
app.post('/mcp-rpc', async (req, res) => {
  await host.handleHttpRequest(req, res);
});

// Register tools and start
host.registerTool(/* ... */);
await host.start();
app.listen(3000);

Documentation

Core Concepts

Transport Modes

  1. Socket Mode (default) - Uses Unix domain sockets for high-performance local IPC

  2. HTTP Mode - Uses HTTP POST requests for web integration and remote access

Context-Based Security

Every tool handler receives a verified context object extracted from JWT tokens:

host.registerTool('read_file', {
  /* tool config */
}, async (context, args) => {
  // context contains verified JWT payload
  if (!context.permissions.includes('read')) {
    throw new Error('Permission denied');
  }
  // Implement tool logic
});

Tool Registration

Tools can be registered with JSON Schema or Zod schemas:

import { z } from 'zod';

// Using Zod schema (auto-converted to JSON Schema)
const schema = z.object({
  name: z.string().min(1),
  age: z.number().positive()
});

host.registerTool('create_user', {
  title: 'Create User',
  description: 'Creates a new user',
  functionName: 'createUser',
  inputSchema: schema // Zod schema auto-converted
}, async (context, args) => {
  // args is validated against schema
});

API Reference

new McpHost(options)

Creates a new MCP host instance.

interface McpHostOptions {
  // Transport mode ('socket' or 'http')
  transport?: 'socket' | 'http';
  
  // Socket mode options
  pipePath?: string;
  
  // HTTP mode options  
  httpPath?: string;
  httpUrl?: string;
  
  // Common options
  secret?: string;
  debug?: boolean;
  start?: boolean;
}

host.registerTool(name, config, handler)

Register a tool with the host.

host.getMCPServerConfig(name, tools, context, options?)

Get MCP server configuration for claude_desktop_config.json.

host.handleHttpRequest(req, res)

Handle HTTP requests (HTTP mode only).

host.start() / host.stop()

Start or stop the host server.

Examples

Check out the examples/ directory for complete examples:

  • simple-example.js - Basic socket mode usage

  • zod-example.js - Zod schema validation

  • http-express-example.js - Express.js HTTP integration

  • http-fastify-example.js - Fastify HTTP integration

  • http-raw-example.js - Raw Node.js HTTP server

Running Examples

# Socket mode example
npm run example

# HTTP mode examples
node examples/http-express-example.js
node examples/http-fastify-example.js

License

MIT

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

-
security - not tested
A
license - permissive license
-
quality - not tested

Resources

Unclaimed servers have limited discoverability.

Looking for Admin?

If you are the server author, to access and configure the admin panel.

Latest Blog Posts

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/botanicastudios/mcp-host-rpc'

If you have feedback or need assistance with the MCP directory API, please join our Discord server