This command enables or disables (toggles) debug mode. In debug mode, IDs for things like states, equipment, provinces, etc are shown when you hover over them which are very useful as they are used in console commands.
The only way this command can be executed. This command will enable tooltip debug mode. In tooltip debug mode, verbose debug data is shown in tooltips - for example, the tooltip that's shown when you hover over a location on the map will show state ID, province ID, etc.