src/
├── tools/              # Tool implementations (one file per tool)
│   ├── echo.py         # Example echo tool
│   └── __init__.py     # Auto-generated tool registry
├── core/               # Dynamic loading framework
│   ├── server.py       # Dynamic MCP server
│   └── utils.py        # Shared utilities
└── main.py             # Entry point
mcp.yaml               # Configuration file
tests/                  # Generated tests

# Command line flag
python src/main.py --http

# Environment variable
MCP_TRANSPORT_MODE=http python src/main.py

# Custom host and port
python src/main.py --http --host localhost --port 8080

# src/tools/weather.py
from core.server import mcp
from core.utils import get_tool_config, get_env_var

@mcp.tool()
def weather(location: str) -> str:
    """Get weather information for a location."""
    
    # Get tool configuration
    config = get_tool_config("weather")
    api_key = get_env_var(config.get("api_key_env", "WEATHER_API_KEY"))
    base_url = config.get("base_url", "https://api.openweathermap.org/data/2.5")
    
    # TODO: Implement weather API call
    return f"Weather for {location}: Sunny, 72°F"

# HTTP API calls
# async with httpx.AsyncClient() as client:
#     response = await client.get(f"{base_url}/weather?q={location}&appid={api_key}")
#     return response.json()

# Database operations  
# async with asyncpg.connect(connection_string) as conn:
#     result = await conn.fetchrow("SELECT * FROM weather WHERE location = $1", location)
#     return dict(result)

# File processing
# with open(file_path, 'r') as f:
#     content = f.read()
#     return {"content": content, "size": len(content)}

tools:
  weather:
    api_key_env: "WEATHER_API_KEY"
    base_url: "https://api.openweathermap.org/data/2.5"
    timeout: 30
  
  database:
    connection_string_env: "DATABASE_URL"
    max_connections: 10

uv run pytest tests/

uv sync

uv run black .
uv run ruff check .
uv run mypy .

# Build image (handles lockfile automatically)
arctl mcp build

# Run container
docker run -i my-mcp:latest