MCP Yahoo Finance

Instructions

Implementation Reference

• src/mcp_yahoo_finance/server.py:37-46 (handler)

  Core handler function that implements the logic to fetch the closing stock price for a given symbol and date using yfinance library.

  def get_stock_price_by_date(self, symbol: str, date: str) -> str:
      """Get the stock price for a given stock symbol on a specific date.
  
      Args:
          symbol (str): Stock symbol in Yahoo Finance format.
          date (str): The date in YYYY-MM-DD format.
      """
      stock = Ticker(ticker=symbol, session=self.session)
      price = stock.history(start=date, period="1d")
      return f"{price.iloc[0]['Close']:.4f}"

• src/mcp_yahoo_finance/server.py:220-235 (registration)

  Registration of all tools including get_stock_price_by_date via generate_tool in the MCP list_tools handler.

  @server.list_tools()
  async def list_tools() -> list[Tool]:
      return [
          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),
          generate_tool(yf.get_news),
          generate_tool(yf.get_recommendations),
          generate_tool(yf.get_option_expiration_dates),
          generate_tool(yf.get_option_chain),
      ]

• src/mcp_yahoo_finance/server.py:243-245 (handler)

  Dispatch handler in MCP call_tool that invokes the get_stock_price_by_date method with arguments and returns the result as TextContent.

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

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

  Helper function generate_tool that dynamically generates the JSON schema for the tool based on function signature, type annotations, and docstring.

  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)

• src/mcp_yahoo_finance/utils.py:7-28 (helper)

  Supporting utility to parse Google-style docstrings for parameter descriptions used in schema generation.

  def parse_docstring(docstring: str) -> dict[str, str]:
      """Parses a Google-style docstring to extract parameter descriptions."""
      descriptions = {}
      if not docstring:
          return descriptions
  
      lines = docstring.split("\n")
      current_param = None
  
      for line in lines:
          line = line.strip()
          if line.startswith("Args:"):
              continue
          elif line and "(" in line and ")" in line and ":" in line:
              param = line.split("(")[0].strip()
              desc = line.split("):")[1].strip()
              descriptions[param] = desc
              current_param = param
          elif current_param and line:
              descriptions[current_param] += " " + line.strip()
  
      return descriptions