Use a carbide vibe engraver and then go over it with a Sharpie.
Also, if the tool can be disassembled, I mark every piece of it (ie my Circular saw is engraved on the handle assembly, skid plate, blade guard, motor housing, and blade housing).
My former Fire Chief was a master carpenter, and he told me about getting tools stolen, and having them show up with old bodies (his) and new handles... minus his markings.
