Alpaca Trading MCP Server

Instructions

Implementation Reference

• src/server.py:315-375 (handler)

  The core handler function implementing the 'place_limit_order' tool. Validates parameters, creates AlpacaOrderRequest with LIMIT type, and delegates to calls.place_order for execution.
  @mcp.tool() def place_limit_order( symbol: str, quantity: float, side: str, limit_price: float, time_in_force: str = "day" ) -> str: """ Place a limit order to buy or sell a stock at a specified price. Args: symbol: Stock symbol (e.g., 'AAPL') quantity: Number of shares to buy or sell (can be fractional) side: Either 'buy' or 'sell' limit_price: Maximum price for buy or minimum price for sell time_in_force: Order duration - 'day', 'gtc' (good till canceled), 'ioc' (immediate or cancel) Returns: Order confirmation details """ # Validate side try: order_side = AlpacaOrderSide(side.lower()) except ValueError: return f"Invalid side: {side}. Must be 'buy' or 'sell'." # Validate time in force try: order_tif = AlpacaTimeInForce(time_in_force.lower()) except ValueError: return f"Invalid time in force: {time_in_force}. Valid options are: day, gtc, ioc, fok" # Create order request order_request = AlpacaOrderRequest( symbol=symbol, qty=float(quantity), side=order_side, type=AlpacaOrderType.LIMIT, time_in_force=order_tif, limit_price=float(limit_price) ) try: order = calls.place_order(trading_client, order_request) return ( f"Limit order placed successfully!\n\n" f"Order ID: {order.id}\n" f"Symbol: {order.symbol}\n" f"Side: {order.side.value}\n" f"Type: {order.type.value}\n" f"Quantity: {order.qty}\n" f"Limit Price: ${order.limit_price:.2f}\n" f"Time in Force: {order.time_in_force.value}\n" f"Status: {order.status.value}\n" f"Created At: {order.created_at}\n" ) except Exception as e: return f"Error placing limit order: {str(e)}"
• src/models.py:87-97 (schema)

  Pydantic BaseModel defining the structure for order requests, including fields specific to limit orders like limit_price. Used directly in the tool handler.
  class AlpacaOrderRequest(BaseModel): symbol: str qty: Union[int, float] side: AlpacaOrderSide type: AlpacaOrderType time_in_force: AlpacaTimeInForce limit_price: Optional[float] = None stop_price: Optional[float] = None client_order_id: Optional[str] = None extended_hours: Optional[bool] = False
• src/calls.py:44-97 (helper)

  Utility function that converts the generic AlpacaOrderRequest into Alpaca SDK's LimitOrderRequest for LIMIT orders and submits it to the trading client.
  def place_order(client: TradingClient, order_details: AlpacaOrderRequest): """ Place an order with flexible order types :param client: Alpaca trading client :param order_details: Order request details :return: Placed AlpacaOrder """ # Map Pydantic model to Alpaca order request based on order type if order_details.type == AlpacaOrderType.MARKET: order_request = MarketOrderRequest( symbol=order_details.symbol, qty=order_details.qty, side=order_details.side, time_in_force=order_details.time_in_force ) elif order_details.type == AlpacaOrderType.LIMIT: if not order_details.limit_price: raise ValueError("Limit price is required for limit orders") order_request = LimitOrderRequest( symbol=order_details.symbol, qty=order_details.qty, side=order_details.side, time_in_force=order_details.time_in_force, limit_price=order_details.limit_price ) elif order_details.type == AlpacaOrderType.STOP: if not order_details.stop_price: raise ValueError("Stop price is required for stop orders") order_request = StopOrderRequest( symbol=order_details.symbol, qty=order_details.qty, side=order_details.side, time_in_force=order_details.time_in_force, stop_price=order_details.stop_price ) elif order_details.type == AlpacaOrderType.STOP_LIMIT: if not (order_details.stop_price and order_details.limit_price): raise ValueError("Both stop and limit prices are required for stop-limit orders") order_request = StopLimitOrderRequest( symbol=order_details.symbol, qty=order_details.qty, side=order_details.side, time_in_force=order_details.time_in_force, stop_price=order_details.stop_price, limit_price=order_details.limit_price ) else: raise ValueError(f"Unsupported order type: {order_details.type}") # Submit order order = client.submit_order(order_request) return AlpacaOrder(**order.__dict__)
• src/models.py:21-43 (schema)

  Enum definitions for order side, type (including LIMIT), and time_in_force used for input validation in the tool handler and order requests.
  class AlpacaOrderSide(str, Enum): BUY = 'buy' SELL = 'sell' class AlpacaOrderType(str, Enum): MARKET = 'market' LIMIT = 'limit' STOP = 'stop' STOP_LIMIT = 'stop_limit' TRAILING_STOP = 'trailing_stop' class AlpacaPositionSide(str, Enum): LONG = 'long' SHORT = 'short' class AlpacaTimeInForce(str, Enum): DAY = 'day' GTC = 'gtc' OPG = 'opg' CLS = 'cls' IOC = 'ioc' FOK = 'fok'