mcp-graphql-enhanced

An enhanced MCP (Model Context Protocol) server for GraphQL that fixes real-world interoperability issues between LLMs and GraphQL APIs.

Drop-in replacement for mcp-graphql with dynamic headers, robust variables parsing, and zero breaking changes.

Key Enhancements

• Dual Transport Supports both STDIO (for local CLI/client tools) and HTTP/JSON-RPC (for external/browser clients).
• Dynamic headers pass Authorization, X-API-Key, etc., via tool arguments (no config restarts)
• Robust variables parsing fixes Query variables must be a null or an object error
• Filtered introspection request only specific types (e.g., typeNames: ["Query", "User"]) to reduce LLM context noise
• Full MCP compatibility works with Claude Desktop, Cursor, Glama
• Secure by default mutations disabled unless explicitly enabled

HTTP / Dual Transport

This server now runs in dual transport mode, supporting both the standard STDIO communication (used by most MCP clients) and a new HTTP JSON-RPC endpoint on port 6274.

This allows external systems, web applications, and direct curl commands to access the server's tools.

Resolving Port Conflicts (EADDRINUSE) and Automatic Port Selection

The server defaults to port 6274. If you encounter an EADDRINUSE: address already in use :::6274 error (common in local development due to stale processes), the server will automatically increment the port and retry (e.g., bind to 6275, then 6276, etc., up to 5 times).

This ensures the server starts successfully even when the default is blocked. Always check the server logs for the final bound port (e.g., [HTTP] Started server on http://localhost:6275) if your curl or client tool fails on the default 6274.

To force a specific port (e.g., for guaranteed external firewall settings), you can still explicitly set the MCP_PORT environment variable:

Testing the HTTP Endpoint

You can test the endpoint using curl as long as the server is running (e.g., via npm run dev):

# Test the health check (assuming the server bound to the default or found the next available port)
curl http://localhost:6274/health

# Example: Test the query tool via JSON-RPC (using port 6275 if 6274 was busy)
curl -X POST http://localhost:6275/mcp -H "Content-Type: application/json" -d '{"jsonrpc":"2.0","method":"query-graphql","params":{"query":"query { __typename }"},"id":1}'

##  Filtered Introspection (New!)
Avoid 50k-line schema dumps. Ask for only what you need:
```@introspect-schema typeNames ["Query", "User"]```
##  Debug & Inspect
Use the official MCP Inspector to test your server live:
```bash
npx @modelcontextprotocol/inspector \
  -e ENDPOINT=https://api.example.com/graphql \
  npx @letoribo/mcp-graphql-enhanced --debug

Environment Variables (Breaking change in 1.0.0)

Note: As of version 1.0.0, command line arguments have been replaced with environment variables.

Examples

# Basic usage
ENDPOINT=http://localhost:3000/graphql npx @letoribo/mcp-graphql-enhanced
# With auth header
ENDPOINT=https://api.example.com/graphql \
HEADERS='{"Authorization":"Bearer xyz"}' \
npx @letoribo/mcp-graphql-enhanced
# Enable mutations
ENDPOINT=http://localhost:3000/graphql \
ALLOW_MUTATIONS=true \
npx @letoribo/mcp-graphql-enhanced
# Use local schema file
ENDPOINT=http://localhost:3000/graphql \
SCHEMA=./schema.graphql \
npx @letoribo/mcp-graphql-enhanced
# Change the HTTP port
MCP_PORT=8080 npx @letoribo/mcp-graphql-enhanced

Claude Desktop Configuration Examples

You can connect Claude Desktop to your GraphQL API using either the npx package (recommended for simplicity) or the Docker image (ideal for reproducibility and isolation).

Option 1: Using npx

{
  "mcpServers": {
    "mcp-graphql-enhanced": {
      "command": "npx",
      "args": ["@letoribo/mcp-graphql-enhanced"],
      "env": {
        "ENDPOINT": "https://your-api.com/graphql"
      }
    }
  }
}

Option 2: Using Docker (auto-pull supported)

{
  "mcpServers": {
    "mcp-graphql-enhanced": {
      "command": "sh",
      "args": [
        "-c",
        "docker run --rm -i -e ENDPOINT=$ENDPOINT -e HEADERS=$HEADERS -e ALLOW_MUTATIONS=$ALLOW_MUTATIONS ghcr.io/letoribo/mcp-graphql-enhanced:main"
      ],
      "env": {
        "ENDPOINT": "https://your-api.com/graphql",
        "HEADERS": "{\"Authorization\": \"Bearer YOUR_TOKEN\"}",
        "ALLOW_MUTATIONS": "false"
      }
    }
  }
}

Option 3: Using node with local build (for development)

If youve cloned the repo and built the project (npm run build outputs to dist/):

{
  "mcpServers": {
    "mcp-graphql-enhanced": {
      "command": "node",
      "args": ["dist/index.js"],
      "env": {
        "ENDPOINT": "https://your-api.com/graphql",
        "ALLOW_MUTATIONS": "true"
      }
    }
  }
}

Resources

• graphql-schema: The server exposes the GraphQL schema as a resource that clients can access. This is either the local schema file, a schema file hosted at a URL, or based on an introspection query.

Available Tools

The server provides two main tools:

1. introspect-schema: This tool retrieves the GraphQL schema or a filtered subset (via typeNames). Use this first if you don't have access to the schema as a resource.
   This uses either the local schema file, a schema file hosted at a URL, or an introspection query.
   Filtered introspection (typeNames) is only available when using a live GraphQL endpoint (not with SCHEMA file or URL).
2. query-graphql: Execute GraphQL queries against the endpoint. By default, mutations are disabled unless ALLOW_MUTATIONS is set to true.

Security Considerations

Mutations are disabled by default to prevent unintended data changes. Always validate HEADERS and SCHEMA inputs in production. Use HTTPS endpoints and short-lived tokens where possible.

Customize for your own server

This is a very generic implementation where it allows for complete introspection and for your users to do whatever (including mutations). If you need a more specific implementation I'd suggest to just create your own MCP and lock down tool calling for clients to only input specific query fields and/or variables. You can use this as a reference.