MCP Yahoo Finance

Instructions

Implementation Reference

• src/mcp_yahoo_finance/server.py:98-120 (handler)

  The core handler function in the YahooFinance class that retrieves and formats historical stock prices using yfinance's Ticker.history method.

  def get_historical_stock_prices(
      self,
      symbol: str,
      period: Literal[
          "1d", "5d", "1mo", "3mo", "6mo", "1y", "2y", "5y", "10y", "ytd", "max"
      ] = "1mo",
      interval: Literal["1d", "5d", "1wk", "1mo", "3mo"] = "1d",
  ) -> str:
      """Get historical stock prices for a given stock symbol.
  
      Args:
          symbol (str): Stock symbol in Yahoo Finance format.
          period (str): The period for historical data. Defaults to "1mo".
                  Valid periods: "1d", "5d", "1mo", "3mo", "6mo", "1y", "2y", "5y", "10y", "ytd", "max"
          interval (str): The interval beween data points. Defaults to "1d".
                  Valid intervals: "1d", "5d", "1wk", "1mo", "3mo"
      """
      stock = Ticker(ticker=symbol, session=self.session)
      prices = stock.history(period=period, interval=interval)
  
      if hasattr(prices.index, "date"):
          prices.index = prices.index.date.astype(str)  # type: ignore
      return f"{prices['Close'].to_json(orient='index')}"

• src/mcp_yahoo_finance/server.py:204-218 (registration)

  Registers all tools including 'get_historical_stock_prices' by generating Tool objects from the YahooFinance methods using generate_tool.

  @server.list_tools()
  async def list_tools() -> list[Tool]:
      return [            
          generate_tool(yf.cmd_run),
          generate_tool(yf.get_recommendations),
          generate_tool(yf.get_news),
          generate_tool(yf.get_current_stock_price),
          generate_tool(yf.get_stock_price_by_date),
          generate_tool(yf.get_stock_price_date_range),
          generate_tool(yf.get_historical_stock_prices),
          generate_tool(yf.get_dividends),
          generate_tool(yf.get_income_statement),
          generate_tool(yf.get_cashflow),
          generate_tool(yf.get_earning_dates),
      ]

• src/mcp_yahoo_finance/server.py:232-234 (helper)

  The dispatch logic in server.call_tool() that matches the tool name and invokes the corresponding handler.

  case "get_historical_stock_prices":
      price = yf.get_historical_stock_prices(**args)
      return [TextContent(type="text", text=price)]

• src/mcp_yahoo_finance/utils.py:31-65 (schema)

  Utility function that inspects the handler function to generate the MCP Tool schema, including input schema from type annotations and docstring descriptions.

  def generate_tool(func: Any) -> Tool:
      """Generates a tool schema from a Python function."""
      signature = inspect.signature(func)
      docstring = inspect.getdoc(func) or ""
      param_descriptions = parse_docstring(docstring)
  
      schema = {
          "name": func.__name__,
          "description": docstring.split("Args:")[0].strip(),
          "inputSchema": {
              "type": "object",
              "properties": {},
          },
      }
  
      for param_name, param in signature.parameters.items():
          param_type = (
              "number"
              if param.annotation is float
              else "string"
              if param.annotation is str
              else "string"
          )
          schema["inputSchema"]["properties"][param_name] = {
              "type": param_type,
              "description": param_descriptions.get(param_name, ""),
          }
  
          if "required" not in schema["inputSchema"]:
              schema["inputSchema"]["required"] = [param_name]
          else:
              if "=" not in str(param):
                  schema["inputSchema"]["required"].append(param_name)
  
      return Tool(**schema)