This is a simple tool that displays information about connected original Xbox controllers. It's designed to be similar to USBView but uses Xbox-specific requests to extract information about the capabilities of the connected controller.
The connected controller must have a libusb or WinUSB driver installed for it for it to show up in the application. Zadig is recommended to install an appropriate driver for the controller.
Devices that act like conventional Xbox game controllers (e.g. game pads, steering wheels, arcade sticks, light guns) can be queried in a "live preview". This shows the current state of the available buttons and axes. This polls the controller via the control endpoint.
There is also an Input Recorder that logs data directly from an input interrupt endpoint. This allows devices that don't report a standard XID descriptor to be inspected.
The Xbox Input Devices section of the xboxdevwiki provides more useful information about Xbox controllers.