Welcome to the Luger Forum. It is a real tool
It is also correct for most byf 41 Lugers. If you examine the markings on the right side of the receiver, you should see either two eagle-over-655, or two eagle-over-135 or a combination of both. The E/135 only occurred in late 1941 production and could have been supplied with an E/135 Tool. Hope this helps!