I'd buy new ones AFTER I gave away his tools and too I'd tell FIL why he got them, embarass you DH
He may get the hint, if not, you may want to know why he focused on something that was yours and why he felt the need to get rid of them~ for whatever reason~ and maybe start a dialogue there.
For fun, take all his tools, let him think you got rid of them, hide them, and then ask him how he feels about you giving HIS things away, and after you both reach a consensus, give him back his tools with this statement "too bad I can't get MY things returned like your tools" Then have him PAY for the replacements.