Save your money and don't buy any junky scuba multitool. Here is what I suggest for a starter kit:
6" adjustable crescent wrench
Set of alan wrenches
Gerber Multi-tool (or similar leatherman)
Standard scuba o-ring assortment
Crescent 6" Adjustable Black Oxide Wrench - Carded - AT26VS - - Amazon.com
EKLIND 10111 Hex-L Key allen wrench - 11pc set SAE Inch Sizes .050-1/4 Short series - - Amazon.com
Gerber MP600 Multi-Plier, Needle Nose, Stainless [07530] - Gerber Multitool - Amazon.com
Amazon.com : Innovative Scuba Concepts Save a Dive O Ring Kit 1 Pieces, RB828 : Sports & Outdoors
That will take care of most issues you will have on a dive excursion.
If you want to really take care of business put together something like this:
View attachment 633925
Save a Dive Kit
1 Pelican 1120 Case {7" x 5"x 3.5")
2 Gerber MultiTool with Pliers
3 Small MultiTools with Sissors
4 Knipex 5" adjustable wrench
5 Cresent Wrench 6"
6 Small Philips/Flat screwdriver
7 Dental picks for Oring removal
8 Hex wench set (7 pcs)
9 Electrical Tape (waterproof)
10 Velcro strips (6 pcs)
11 Bungie cord (1/8" 6ft)
12 Silver Sharpie
13 Oring Kits (2 w/various)
14 Plugs for 1st Stages (lp/hp)
15 O2 Lube
16 Silicone Lube
17 Mineral Oil (small vial)
18 USA Quarter (shearwater battery cap)
19 IP Guage
20 LP Air Nozzle
21 QC6 Connector (offboard gas)
22 SPG 1" button guage
23 DIN Inserts (x2)
24 SPG spools (x2)
25 Overpressure valve
26 Super Glue
27 Double Ender clip 3"
28 Quick Links & S-Biner clips
29 Small Zip Ties (x20)
30 Q-Tips