I have to somewhat agree with everyone here... I had an ACF for 17 years (I miss him!). He never lived in anything smaller than a 10 and spent the last 5 or so years of his life in a 15. 15 gallons with a strong filter was just about perfect.
I also have a Petco bookshelf tank and it's just about the right size for the betta that lives there, so no, I wouldn't put an adult ACF in there. Even the males grow to be quite a bit bigger than 3 inches. 3 inches is just the body length, not counting legs. They're incredibly active swimmers and swim laps in their tank all day long.
Moreover, your frog is going to uproot pretty much any plant you put in your tank the second he gets startled and tries to find a place to hide.
I'm confused by whoever said you have to lower the water level for these frogs though, especially in a Petco bookshelf tank that's the height of a 2.5 gallon.