Come on.
You got to be kidding.
Who advised such a small tank for a frog ?

If you don't like to spend more room, look into another hobby....
Maybe stamp collecting ?

I am,not used to gallon and inches,
But what I looked up on the size is it is a tank of 40x20x25cm.
That is really to small to provide enough space.
But well, maybe it is common use over there, although doubtful.
Around here a minimum for the smallest species would be no less then 40x40x40cm, although in my opinion it can be even a small size for a couple of thumbnails.
This kind of sizes are only for my offspring to grow the first month or 4.