From what I've read it was normal to attach the tools to the vehicle, mask off the periscopes and vison slits and then hose the whole tank down with paint. So the tools should be the same as the base colour of the vehicle.
But most modelers do paint the wooden parts a wooden sort of colour and the metal bits steel just to add more contrast. Call it artistic license, it's more interesting than painting the whole darn thing green or brown.
Personally I leave the tools off, paint them, and then add them last. I just can't seem to get to the back sides of the tools without making a mess if I attach them and then paint them later. And one tip I've been given, paint the metal bits a dark grey and then rub a pencil on a piece of paper to get an accumulation of graphite (lead). Then rub this on you finger tip or a cotton swab and scrub it over the metal bits to just give it a light metallic sheen.