WeMo MCP Server

Instructions

Dictionary containing:
- device_count: Number of cached devices
- devices: List of device names and IPs

Implementation Reference

• src/wemo_mcp_server/server.py:517-577 (handler)

  The list_devices function is implemented as an MCP tool, querying the _device_cache and falling back to a persistent JSON cache if the in-memory cache is empty.

  @mcp.tool()
  async def list_devices() -> dict[str, Any]:
      """List all discovered WeMo devices from the cache.
  
      Returns a list of devices that were found in previous network scans.
      Run scan_network first to populate the device cache.
  
      Returns
      -------
          Dictionary containing:
          - device_count: Number of cached devices
          - devices: List of device names and IPs
  
      """
      try:
          # Get unique devices from in-memory cache (device cache may have duplicates by name and IP)
          unique_devices: dict[str, dict[str, Any]] = {}
          for key, device in _device_cache.items():
              device_name = device.name
              if device_name not in unique_devices:
                  unique_devices[device_name] = {
                      "name": device_name,
                      "ip_address": getattr(device, "host", "unknown"),
                      "model": getattr(device, "model", "Unknown"),
                      "type": type(device).__name__,
                      "source": "memory",
                  }
  
          # If in-memory cache is empty, fall back to persistent JSON cache
          if not unique_devices:
              cached_data = _cache_manager.load()
              if cached_data:
                  for _key, info in cached_data.items():
                      if not isinstance(info, dict):
                          continue
                      name = info.get("name", _key)
                      if name not in unique_devices:
                          unique_devices[name] = {
                              "name": name,
                              "ip_address": info.get("host", "unknown"),
                              "model": info.get("model_name") or info.get("model", "Unknown"),
                              "type": info.get("device_type", "Unknown"),
                              "source": "file_cache",
                          }
  
          result: dict[str, Any] = {
              "device_count": len(unique_devices),
              "devices": list(unique_devices.values()),
          }
          if unique_devices and all(d.get("source") == "file_cache" for d in unique_devices.values()):
              result["note"] = (
                  "Devices loaded from persistent cache file (server was restarted). "
                  "Control commands will automatically reconnect to devices as needed."
              )
          return result
      except Exception as e:
          logger.error(f"Error listing devices: {e}", exc_info=True)
          error_response = build_error_response(e, "List devices")
          error_response.update({"device_count": 0, "devices": []})
          return error_response