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McGravity

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A proxy tool for composing multiple MCP servers into one unified endpoint. Scale your AI tools by load balancing requests across multiple MCP servers, similar to how Nginx works for web servers.

McGravity

About

McGravity is a tool that connects multiple MCP (Machine Communication Protocol) servers into one unified service. It lets you reuse the same MCP server and scale underlying MCP server connections almost infinitely.

The current version works as a basic CLI tool, but McGravity will grow to become a full-featured proxy for MCP servers - like Nginx but for modern Gen AI tools and servers.

Why McGravity?

Without McGravity:
┌─────────┐     ┌─────────┐
│ Client  │────▶│MCP      │
│         │     │Server 1 │
└─────────┘     └─────────┘
    │
    │           ┌─────────┐
    └──────────▶│MCP      │
                │Server 2 │
                └─────────┘

With McGravity:
┌─────────┐     ┌─────────┐     ┌─────────┐
│ Client  │────▶│McGravity│────▶│MCP      │
│         │     │         │     │Server 1 │
└─────────┘     └─────────┘     └─────────┘
                     │
                     │          ┌─────────┐
                     └─────────▶│MCP      │
                                │Server 2 │
                                └─────────┘

McGravity solves these problems:

  • Connect to multiple MCP servers through one endpoint
  • Balance load between MCP servers
  • Provide a single point of access for your applications

Installation

# Install dependencies
bun install

# Build the project into a single executable
bun build src/index.ts --compile --outfile mcgravity

Docker

McGravity is available on Docker Hub: tigranbs/mcgravity.

docker pull tigranbs/mcgravity

# Basic usage
docker run -p 3001:3001 tigranbs/mcgravity http://mcp1.example.com http://mcp2.example.com

# With custom host and port
docker run -p 4000:4000 tigranbs/mcgravity --host 0.0.0.0 --port 4000 http://mcp1.example.com

Usage

Basic command:

./mcgravity <mcp-server-address1> <mcp-server-address2> ...

With options:

./mcgravity --host localhost --port 3001 http://mcp1.example.com http://mcp2.example.com

Using configuration file:

./mcgravity --config config.yaml

Options

  • --host <host>: Host to bind the server to (default: localhost)
  • --port <port>: Port to bind the server to (default: 3001)
  • --config <path>: Path to the config file (default: config.yaml)
  • --mcp-version <version>: Version of the MCP server (default: 1.0.0)
  • --mcp-name <name>: Name of the MCP server (default: mcgravity)
  • --help: Show help information

Configuration

McGravity can be configured using a YAML file. See config.example.yaml for a sample configuration:

name: mcgravity
version: 1.0.0
description: A simple MCP server

servers:
  echo-server:
    url: http://localhost:3000/sse
    name: echo-server
    version: 1.0.0
    description: A simple echo server
    tags:
      - echo

You can run the included echo server example for testing:

# Start the echo server first
bun examples/echo-server.ts

# Then start McGravity pointing to the echo server
./mcgravity --config config.yaml

Examples

Start McGravity with default settings:

./mcgravity http://mcp1.example.com http://mcp2.example.com

Specify host and port:

./mcgravity --host 0.0.0.0 --port 4000 http://mcp1.example.com http://mcp2.example.com

Running Tests

To run all tests:

bun test

To run integration tests only:

bun run test:integration

Integration Tests

The integration tests verify that McGravity can:

  1. Connect to an MCP server (the example echo server)
  2. Correctly proxy capabilities from the target MCP server
  3. Pass requests from clients to the target MCP server and return responses

For more details about the test suite, see the test README.

The tests are automatically run in GitHub Actions CI on push and PR events.

Future Plans

McGravity will expand to include:

  • Web interface for monitoring
  • Advanced load balancing
  • MCP server health checks
  • Authentication and access control
  • Plugin system for custom integrations

Development

TypeScript and Code Style

This project uses:

  • TypeScript with Bun runtime
  • ESLint for code linting with TypeScript-specific rules
  • Prettier for code formatting

The configuration is optimized for Bun with appropriate TypeScript settings for the runtime environment.

Run the following commands:

# Format code with Prettier
bun run format

# Check if code is properly formatted
bun run format:check

# Lint code with ESLint
bun run lint

# Fix auto-fixable linting issues
bun run lint:fix

VS Code is configured to format code on save and provide linting information when the recommended extensions are installed.

Contributing

Contributions are welcome! Feel free to open issues or submit pull requests.

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