MCP/
├── src/
│   ├── server.py              # MCP server entry point
│   ├── auth/
│   │   ├── __init__.py
│   │   ├── oauth.py           # OAuth 2.0 flow handler with popup
│   │   └── credentials.py     # Secure credential storage (keyring)
│   ├── gateway/
│   │   ├── __init__.py
│   │   ├── api_client.py      # Generic REST/GraphQL HTTP client
│   │   └── handlers.py        # Request/response transformation
│   ├── models/
│   │   ├── __init__.py
│   │   └── data_models.py     # Generic Pydantic data models
│   └── tools/
│       ├── __init__.py
│       └── mcp_tools.py       # MCP tool definitions for Claude
├── config/
│   └── api_configs.json       # API service configurations
├── tests/                     # Unit and integration tests
├── .env.example               # Environment variables template
├── .gitignore                 # Excludes secrets and build artifacts
├── requirements.txt           # Python dependencies
└── README.md                  # This file

1. Claude invokes tool (e.g., fetch_data)
        ↓
2. MCP checks credentials in keyring
        ↓
3a. Valid token  →  Proceed with API call
3b. Missing/Expired  →  Open browser popup for OAuth
        ↓
4. User logs in via browser
        ↓
5. Local callback server receives auth code
        ↓
6. Exchange auth code for access token
        ↓
7. Store token in keyring
        ↓
8. Resume original tool call

# Clone the repository
cd /Users/chawengwit/Documents/MCP

# Create virtual environment
python -m venv venv
source venv/bin/activate  # On Windows: venv\Scripts\activate

# Install dependencies
pip install -r requirements.txt

# Copy environment template
cp .env.example .env
# Edit .env with your OAuth credentials and API settings

# OAuth credentials (per provider)
OAUTH_CLIENT_ID=your_client_id
OAUTH_CLIENT_SECRET=your_client_secret
OAUTH_REDIRECT_URI=http://localhost:8765/callback

# Server settings
MCP_LOG_LEVEL=INFO              # DEBUG | INFO | WARN | ERROR
MCP_LOG_FILE=                   # Optional path to log file (default: stderr only)
MCP_DEBUG=false                 # Enable verbose request tracing
MCP_MAX_RESPONSE_BYTES=1048576  # Response size cap (1 MB default)
OAUTH_CALLBACK_PORT=8765

{
  "apis": {
    "example_api": {
      "base_url": "https://api.example.com",
      "type": "rest",
      "auth": {
        "method": "oauth2",
        "provider": "custom",
        "authorize_url": "https://auth.example.com/oauth/authorize",
        "token_url": "https://auth.example.com/oauth/token",
        "scopes": ["read", "write"]
      },
      "endpoints": {
        "get_users": {"method": "GET", "path": "/users"},
        "create_user": {"method": "POST", "path": "/users"}
      }
    }
  }
}

python -m src.server

{
  "mcpServers": {
    "data-gateway": {
      "command": "python",
      "args": ["-m", "src.server"],
      "cwd": "/Users/chawengwit/Documents/MCP"
    }
  }
}

{
  "data": <api response>,
  "metadata": { "source": "...", "endpoint": "...", "timestamp": "...", "duration_ms": 142 }
}

{
  "error": { "code": "AUTH_REQUIRED", "message": "...", "details": { ... } }
}

MCP_DEBUG=true MCP_LOG_LEVEL=DEBUG python -m src.server