I know this might seem dumb to some people cause it's 'just an insect' but if you're really going to keep him as a pet long term I would recommend reading some about how to properly care for him or her. From what I can see and some brief reading the enclosure seems pretty good except you may want some absorbent substrate not just rock. https://www.keepinginsects.com/praying-mantis/care/
Also the previous article I linked said they get their water from humidity so a bottle cap with water may not work well. The article said something about spraying in the enclosure with a spray bottle once in a while. Don't directly spray the mantis though.
I will add some dirt and possibly a tiny well in the corner using the bottle cap.