Whether or not you can clear the codes is kinda a trick question, one can clear certain codes after 3 drive cycles IF the problem goes away and the malfunctioning part operates correctly, other codes will not clear until after 40 drive cycles, However, on some US model vehicles, ( I am uncertain about MB) if you disconnect the battery for 5-10 minutes, the code will clear, but the monitors will be at 'not ready' for a length of time, this is only a problem if you are in an area that has OBD emissions testing like here in St Louis, the festering, oozing ulcer on the otherwise beautiful state of Missouri.
That scan tool sounds like it will work, the thing with it is that it reads onlly generic codes like P0101, MB may have some manufacturer specific codes (I am not certain about this), like P1456, some scanners are manufacturer specific.OBD was implemented in 96, so a push was made to have all vehicle manufacturers use the same codes, this is the case in newer models from about 99 on, but alot of 96-98's still will have a few Manufacturer codes.
Hope this helps, another good web site is www.necvecs.com,
I think thats the right address, damn, its early and I have only had 1 cup of coffee, can't think, must have caffeine and nicotine, the breakfast of champions...
Really, a scan tool is invaluable for 96 and newer cars. Takes alot of guess work out, they will not exactly ID a problem in most cases, but will point one in the right direction.