MCU Output Driver Verification
A 2N7002 is a poor choice for an STM32 MCU, since you'll be limited to ~3V output voltage. 

I suggest using something like an AO3418, which is inexpensive and guaranteed to have less than 85m\$\Omega\$ Rds(on) with 2.5V drive (at Tj=25°C). That would allow you to safely drive at least 1A with 3.3V drive over a reasonable temperature range, and it will have very low 'on' drop- typically something like 10mV when driving 200mA. 

It might be nice to put a series resistor and LED across the load terminals for visual indication of the output state- it will also pull up the output so someone troubleshooting will be able to use a multimeter on voltage range to check the output.

The output as shown has no short-circuit protection, so if a screwdriver or probe slips, the output could be damaged if the 12V supply can supply more than a few amperes. If your 12V line can be limited in current, then that is another reason to make the output a bit beefier, so it can survive a momentary short-circuit.