Can someone summarize what a Chaplain’s assistant does in garrison?

Chaplain Assistant is assigned a weapon and needs to be proficient with it, Chaplain may NOT handle a weapon.
This is a great opportunity for you to learn stuff outside your MOS. I don't mean 56 series stuff, but more staff stuff, which will come in handy when you make SGT. Dig into your work, get involved. Part of the Chaplains job is to assess morale of the troops and implement small things to raise morale. You are an extension of the Chap's eyes and ears. The Chap reports directly to the BN CDR. Do a great job (and don't forget your intel knowledge and duties) and you could see some serious fast tracking.

Admin duties, driving the chaplain, set up/tear down the area of service....protect the chaplain.

Your kind of like the Chaplains Secretary/Driver/Gofer, Set Church up for the weekly sermon stuff

I would of checked first lol

I was a chaplains asst on active duty when it deployed or being involved with unit morale I would work Sunday services and in charge of counting monies with select individuals from the congregation, plan unit trips for married and unmarried soldiers, lead the army substance abuse program classes, I was a a trainer for suicide awareness, kept my chaplains schedule updated, attended some meeting on be half of my chaplain if he had a prior engagement that could not be rescheduled. In the unit I was assigned was an infantry unit so we were always going to the range and that was a great place to start talking and checking on fellow soldiers and check the pulse if you will of the unit.

You're responsible for all clerical duties pertaining to your chaplain. You take him wherever the troops are so he/she can do their job. You set up services wherever they are several times a day, or, in the field, training areas, chapel, wherever the troops are the chaplain should make a visit. You're responsible for keeping up with troop numbers, religious preference and changes. You're the eyes and ears of the chaplain when it comes to caring for our troops. You'll know before the chaplain if a soldier is having problems, so stay sharp.

Your his/her secretary, organizer, driver, security. You set up all religious services and tear them down. You need to ask for the online courses for 56M and go to school. Deployment was a better gig, more soldiering. Your the right hand of the Chaplain.