MCP OpenAI Extended

Extended Model Context Protocol (MCP) server for OpenAI with GPT-5 family support, including specialized Codex models.

Features

• ✅ GPT-5 family support (gpt-5, gpt-5.1, gpt-5.2, chat-latest/pro/mini/nano/codex variants)

• ✅ GPT-4o and o1 series support

• ✅ Responses API support for Codex models (*codex*)

• ✅ Automatic API endpoint selection (Responses API for codex, Chat Completions for others)

• ✅ Works with Claude Desktop, Claude Code, and any MCP-compatible client

Related MCP server: OpenAI API MCP Server

Supported Models

GPT-5 Family

• gpt-5-codex - Specialized for code and design reviews (default, uses Responses API)

• gpt-5.3-codex

• gpt-5.3-codex-spark

• gpt-5.2-chat-latest

• gpt-5.2-pro

• gpt-5.2

• gpt-5.2-codex

• gpt-5.1-chat-latest

• gpt-5.1-codex

• gpt-5.1-codex-mini

• gpt-5.1-codex-max

• gpt-5.1

• gpt-5-chat-latest

• codex-mini-latest

• gpt-5-pro

• gpt-5

• gpt-5-mini

• gpt-5-nano

Note: Newer Codex model IDs may require account-level access before they work in API requests.

GPT-4 Series

• gpt-4o - GPT-4 Omni

• gpt-4o-mini - Smaller GPT-4o

o1 Series

• o1 - Reasoning model

• o1-preview - Reasoning model preview

• o1-mini - Smaller reasoning model

Installation

NPM (Recommended)

npm install -g @kent013/mcp-openai-extended

Via npx (GitHub)

npx github:kent013/mcp-openai-extended

Local Development

git clone https://github.com/kent013/mcp-openai-extended.git
cd mcp-openai-extended
npm install
npm run build

Configuration

⚠️ Security Warning

NEVER commit your API key to version control!

• Keep your OPENAI_API_KEY in environment variables or secure configuration files

• Add configuration files containing API keys to .gitignore

• If you accidentally commit an API key, revoke it immediately at https://platform.openai.com/api-keys

• Rotate your API keys regularly

Claude Desktop / Claude Code

Add to your .mcp.json or claude_desktop_config.json:

{
  "mcpServers": {
    "openai": {
      "command": "npx",
      "args": ["-y", "@kent013/mcp-openai-extended"],
      "env": {
        "OPENAI_API_KEY": "your-openai-api-key-here"
      }
    }
  }
}

Local Development

{
  "mcpServers": {
    "openai": {
      "command": "node",
      "args": ["/path/to/mcp-openai-extended/dist/index.js"],
      "env": {
        "OPENAI_API_KEY": "your-openai-api-key-here"
      }
    }
  }
}

Usage

The server provides a single tool: openai_chat

Default model is gpt-5-codex (automatically uses Responses API).

Example: Design Review with GPT-5.2 Codex (Default)

{
  "name": "openai_chat",
  "arguments": {
    "messages": [
      {
        "role": "system",
        "content": "You are an experienced system architect."
      },
      {
        "role": "user",
        "content": "Review this code:\n\n```php\n$user = User::find($id);\nMail::to($user->email)->send(new TestMail());\n```"
      }
    ]
    // model defaults to "gpt-5-codex"
  }
}

Example: General Reasoning with GPT-5 Chat Latest

{
  "name": "openai_chat",
  "arguments": {
    "messages": [
      {
        "role": "user",
        "content": "Explain quantum computing in simple terms"
      }
    ],
    "model": "gpt-5-chat-latest"
  }
}

API Endpoints

This server automatically selects the appropriate OpenAI API endpoint:

• Responses API (/v1/responses): For Codex models (*codex*)

• Chat Completions API (/v1/chat/completions): For all other models (gpt-4o, gpt-5-chat-latest, etc.)

Environment Variables

• OPENAI_API_KEY (required): Your OpenAI API key

Getting Your API Key

1. Visit https://platform.openai.com/api-keys

2. Create a new API key

3. Store it securely - never share or commit it to version control

4. Set appropriate usage limits to prevent unexpected charges

Best Practices

• Use environment-specific API keys (development, staging, production)

• Enable usage alerts in your OpenAI account

• Regularly review API usage and rotate keys

• Use OpenAI's API key restrictions feature to limit key permissions

Development

# Install dependencies
npm install

# Build
npm run build

# Run locally
node dist/index.js

Contributing

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

License

MIT

Credits

Based on mcp-openai by mzxrai.

Extended to support GPT-5 family and specialized models.