How to Install OpenAPI MCP Server

Introduction

OpenAPI MCP Server is a powerful tool that enables AI assistants like Claude and Cursor to search, explore, and understand OpenAPI specifications through the Model Context Protocol (MCP). This server acts as a bridge between AI models and complex API documentation, allowing them to interpret and work with APIs more effectively. In this tutorial, we'll walk through the installation process step by step, covering multiple installation methods and configuration options.

The OpenAPI MCP Server, developed by Jan Wilmake, provides a unique capability to AI assistants, enabling them to:

• Get an overview of any OpenAPI specification
• Search through API endpoints and operations
• Retrieve detailed information about specific API endpoints
• Work with both JSON and YAML format specifications

Tired of Postman? Want a decent postman alternative that doesn't suck?

Apidog is a powerful all-in-one API development platform that's revolutionizing how developers design, test, and document their APIs.

Unlike traditional tools like Postman, Apidog seamlessly integrates API design, automated testing, mock servers, and documentation into a single cohesive workflow. With its intuitive interface, collaborative features, and comprehensive toolset, Apidog eliminates the need to juggle multiple applications during your API development process.

Whether you're a solo developer or part of a large team, Apidog streamlines your workflow, increases productivity, and ensures consistent API quality across your projects.

Prerequisites

Before installing the OpenAPI MCP Server, ensure you have the following:

• Node.js (version 16.17.0 or higher)
• npm (typically comes with Node.js)
• An MCP-compatible client such as:
  • Claude Desktop
  • Cursor AI IDE
  • Other MCP-compatible clients

If you don't have Node.js installed, visit nodejs.org to download and install the latest LTS version for your operating system.

Installation Methods

There are multiple ways to install the OpenAPI MCP Server. We'll cover the three main approaches:

1. Installation via Smithery (recommended for beginners)
2. Installation via npx
3. Manual installation from GitHub

Method 1: Installation via Smithery

Smithery is a registry and installer for MCP servers that makes the installation process simple and straightforward. This is the recommended approach for most users, especially those new to MCP servers.

1. Open your terminal or command prompt

2. Install the OpenAPI MCP Server using Smithery Run the following command:

   npx -y @smithery/cli install @janwilmake/openapi-mcp-server --client claude
   

   This command:

   • Uses npx to run the Smithery CLI without installing it globally
   • Installs the OpenAPI MCP Server
   • Configures it for use with Claude Desktop

3. Verify the installation Once the installation is complete, Smithery will display a confirmation message showing the server has been installed and configured.

4. Restart Claude Desktop If Claude Desktop was already running, you'll need to restart it for the changes to take effect.

Method 2: Installation via npx

If you prefer not to use Smithery, you can install the OpenAPI MCP Server directly using npx:

1. Open your terminal or command prompt

2. Run the initialization command

   npx openapi-mcp-server@latest init
   

3. Follow the interactive prompts The initialization script will guide you through the setup process:

   • Select your MCP client (Claude Desktop, Cursor, etc.)
   • Configure the server port (default is usually fine)
   • Set additional options as needed

4. Complete the setup The script will install necessary dependencies, create configuration files, and provide instructions for the next steps.

5. Restart your MCP client Restart Claude Desktop or your chosen MCP client to apply the changes.

Method 3: Manual Installation from GitHub

For advanced users or those who want more control over the installation process, you can install the OpenAPI MCP Server directly from GitHub:

1. Clone the repository

   git clone https://github.com/janwilmake/openapi-mcp-server.git
   

2. Navigate to the project directory

   cd openapi-mcp-server
   

3. Install dependencies

   npm install
   

4. Configure the server Create or modify the configuration file (usually found in the project directory) according to your needs.

5. Start the server

   node index.js
   

6. Configure your MCP client You'll need to manually configure your MCP client to connect to the server running on the specified port (usually 3000 by default).

Understanding the OpenAPI MCP Server Architecture

The OpenAPI MCP Server works through a three-step process:

1. Discovery: It identifies the OpenAPI specification you're interested in.
2. Summary: It generates a simple language summary of the API.
3. Analysis: It examines specific endpoints in detail and translates complex API structures into simple language.

This architecture allows AI assistants to effectively navigate and understand complex API documentation without having to parse raw OpenAPI specifications directly.

Configuration Options

After installation, you may want to customize your OpenAPI MCP Server configuration:

Server Port

By default, the OpenAPI MCP Server runs on port 3000. If you need to change this (for example, if another service is already using that port):

1. Open the configuration file (location depends on installation method)
2. Locate the port setting
3. Change it to your preferred port
4. Restart the server

API Sources

The OpenAPI MCP Server can search through various API repositories. To customize these sources:

1. Edit the server configuration
2. Modify the sources array to include your preferred API repositories
3. Save and restart the server

Rate Limiting

To prevent excessive API calls and ensure stable performance:

1. Configure rate limiting settings in the configuration file
2. Set values appropriate for your usage patterns
3. Restart the server to apply changes

Testing Your Installation

Once installed, you can test if your OpenAPI MCP Server is working correctly:

1. Start Claude Desktop or your preferred MCP client

2. Ask about an API Try a simple query like:

   Find information about the Stripe API
   

   or

   Explain how to use the GitHub API's repository endpoints
   

3. Observe the response If correctly installed, your AI assistant will:

   • First get an overview of the requested API
   • Then retrieve specific operation details as needed

Troubleshooting Common Issues

Server Fails to Start

Issue: The server doesn't start or crashes immediately. Solution:

• Check if you have the correct Node.js version (16.17.0 or higher)
• Ensure no other service is using the same port
• Check for errors in the console output

Connection Issues

Issue: Your MCP client can't connect to the server. Solution:

• Verify the server is running (check the terminal)
• Ensure the port configuration matches between server and client
• Check your firewall settings

API Not Found

Issue: The server can't find information about specific APIs. Solution:

• Verify the API name is correct
• Check if the API has an OpenAPI specification available
• Consider adding custom API sources to the configuration

Upgrading Your Installation

OpenAPI MCP Server is actively developed, with new versions being released regularly. To upgrade:

If Installed via Smithery

npx -y @smithery/cli upgrade @janwilmake/openapi-mcp-server --client claude

If Installed via npx

npx openapi-mcp-server@latest upgrade

If Installed Manually

1. Navigate to the project directory
2. Pull the latest changes from GitHub

   git pull origin main
   

3. Reinstall dependencies

   npm install
   

4. Restart the server

Conclusion

The OpenAPI MCP Server opens up new possibilities for AI assistants to work with APIs in a more intuitive way. By following this installation guide, you've enabled your AI assistant to navigate, understand, and utilize complex API documentation through natural language interactions.

Remember that OpenAPI MCP Server v2 is still a work in progress, focusing primarily on API exploration and context provision rather than direct endpoint execution. While it doesn't currently support executing API endpoints directly due to authentication challenges, it's an excellent tool for understanding APIs and generating code for API interactions.

As the MCP ecosystem continues to evolve, we can expect even more powerful capabilities in future releases. Stay updated by following the project on GitHub and joining discussions in the MCP community.

Now that you have successfully installed the OpenAPI MCP Server, you can start exploring APIs with your AI assistant in a more natural and intuitive way!