My two tips for jawfish are 1) make sure you have a lid and 2) don't overly worry about substrate depth but do worry about having suitable burrow material. I'll explain that last one as it's connected to the first point in that jawfish only tend to jump in the beginning when they don't yet have a suitable burrow, so no hideout can spook them but once it's dug they are less likely to leap out.
The second point about building material is key because they need different sized sand, rubble or shells in which to construct a burrow that doesn't collapse (they tend to need about 4-6" depth in total as they like to be abe to sit vertically plus have a little extra room). They are like little bulldozers so will bring the material to their chosen spot, so all you need to do is add good building blocks to the rough area and it will soon be used. A pipe as base for the burrow can work well but they can often build quite a network in time.
Just in case you aren't aware bluespots aren't the easiest jawfish to keep long term so I'd make sure you know how tricky they can be before getting one or look at a much hardier species like the pearly jaw above.
