Banxico MCP Server

Instructions

Implementation Reference

• banxico_mcp_server.py:483-509 (handler)

  The get_udis_data tool handler, registered via @mcp.tool() decorator. Fetches UDIS data from Banxico SIE API endpoint 'series/SP68257/datos', applies optional limit to recent data points, and formats the response using format_exchange_rate_data.

  @mcp.tool()
  async def get_udis_data(limit: Optional[int] = 30) -> str:
      """
      Get UDIS (Investment Units) data from Banxico.
      
      Args:
          limit: Maximum number of recent data points (default: 30)
          
      Returns:
          Current and historical UDIS values
      """
      if not BANXICO_TOKEN:
          return "Error: BANXICO_API_TOKEN environment variable not set. Please configure your API token."
      
      endpoint = "series/SP68257/datos"
      data = await make_banxico_request(endpoint, BANXICO_TOKEN)
      
      if not data:
          return "Failed to retrieve UDIS data. Please check your API token and network connection."
      
      # Apply limit if specified
      if limit and data.get("bmx", {}).get("series"):
          for series in data["bmx"]["series"]:
              if "datos" in series and len(series["datos"]) > limit:
                  series["datos"] = series["datos"][-limit:]
      
      return format_exchange_rate_data(data)

• banxico_mcp_server.py:483-483 (registration)

  Registration of the get_udis_data tool using FastMCP's @mcp.tool() decorator, which also derives schema from function signature and docstring.

  @mcp.tool()

• banxico_mcp_server.py:43-69 (helper)

  Helper function used by get_udis_data to make authenticated HTTP requests to Banxico API.

  async def make_banxico_request(endpoint: str, token: str) -> dict[str, Any] | None:
      """
      Make a request to the Banxico SIE API with proper error handling.
      
      Args:
          endpoint: The API endpoint to call (without base URL)
          token: The Banxico API token
          
      Returns:
          JSON response data or None if request failed
      """
      url = f"{BANXICO_API_BASE}/{endpoint}"
      headers = {"User-Agent": USER_AGENT}
      params = {"token": token}
      
      try:
          async with httpx.AsyncClient() as client:
              response = await client.get(url, headers=headers, params=params, timeout=30.0)
              response.raise_for_status()
              return response.json()
      except httpx.HTTPError as e:
          logger.error(f"HTTP error occurred: {e}")
          return None
      except Exception as e:
          logger.error(f"An error occurred: {e}")
          return None

• banxico_mcp_server.py:71-122 (helper)

  Helper function used by get_udis_data to format the API response data into a readable string representation.

  def format_exchange_rate_data(data: dict[str, Any]) -> str:
      """
      Format exchange rate data into a readable string.
      
      Args:
          data: Raw JSON response from Banxico API
          
      Returns:
          Formatted string with exchange rate information
      """
      if not data or "bmx" not in data:
          return "No data available"
      
      series_list = data["bmx"].get("series", [])
      if not series_list:
          return "No series data found"
      
      result = []
      for series in series_list:
          series_title = series.get("titulo", "Unknown Series")
          series_id = series.get("idSerie", "Unknown ID")
          result.append(f"Series: {series_title} (ID: {series_id})")
          
          datos = series.get("datos", [])
          if not datos:
              result.append("  No data points available")
          else:
              result.append(f"  Total data points: {len(datos)}")
              # Show first few and last few data points
              if len(datos) <= 10:
                  for dato in datos:
                      fecha = dato.get("fecha", "Unknown date")
                      valor = dato.get("dato", "N/A")
                      result.append(f"  {fecha}: {valor}")
              else:
                  # Show first 5
                  for i, dato in enumerate(datos[:5]):
                      fecha = dato.get("fecha", "Unknown date")
                      valor = dato.get("dato", "N/A")
                      result.append(f"  {fecha}: {valor}")
                  
                  result.append(f"  ... ({len(datos) - 10} more data points) ...")
                  
                  # Show last 5
                  for dato in datos[-5:]:
                      fecha = dato.get("fecha", "Unknown date")
                      valor = dato.get("dato", "N/A")
                      result.append(f"  {fecha}: {valor}")
          
          result.append("")  # Empty line between series
      
      return "\n".join(result)