mcp-graphql

A Model Context Protocol server that enables LLMs to interact with GraphQL APIs. This implementation provides schema introspection and query execution capabilities, allowing models to discover and use GraphQL APIs dynamically.

Usage

Run mcp-graphql with the correct endpoint, it will automatically try to introspect your queries.

Environment Variables (Breaking change in 1.0.0)

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

Environment Variable	Description	Default
ENDPOINT	GraphQL endpoint URL	http://localhost:4000/graphql
HEADERS	JSON string containing headers for requests	{}
ALLOW_MUTATIONS	Enable mutation operations (disabled by default)	false
NAME	Name of the MCP server	mcp-graphql
SCHEMA	Path to a local GraphQL schema file or URL (optional)	-

Examples

# Basic usage with a local GraphQL server
ENDPOINT=http://localhost:3000/graphql npx mcp-graphql

# Using with custom headers
ENDPOINT=https://api.example.com/graphql HEADERS='{"Authorization":"Bearer token123"}' npx mcp-graphql

# Enable mutation operations
ENDPOINT=http://localhost:3000/graphql ALLOW_MUTATIONS=true npx mcp-graphql

# Using a local schema file instead of introspection
ENDPOINT=http://localhost:3000/graphql SCHEMA=./schema.graphql npx mcp-graphql

# Using a schema file hosted at a URL
ENDPOINT=http://localhost:3000/graphql SCHEMA=https://example.com/schema.graphql npx mcp-graphql

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. 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.

2. query-graphql: Execute GraphQL queries against the endpoint. By default, mutations are disabled unless ALLOW_MUTATIONS is set to true.

Installation

Installing via Smithery

To install GraphQL MCP Server for Claude Desktop automatically via Smithery:

npx -y @smithery/cli install mcp-graphql --client claude

Installing Manually

It can be manually installed to Claude:

{
    "mcpServers": {
        "mcp-graphql": {
            "command": "npx",
            "args": ["mcp-graphql"],
            "env": {
                "ENDPOINT": "http://localhost:3000/graphql"
            }
        }
    }
}

Security Considerations

Mutations are disabled by default as a security measure to prevent an LLM from modifying your database or service data. Consider carefully before enabling mutations in production environments.

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.