Legal Question in Real Estate Law in California

Unless you are a licensed contractor, you will get no help from the law. In fact, if you pursued legal action you would be ordered to repay anything he or she already paid you and he or she could sell your tools if you didn't pay. So if you are not licensed, you have no choice but to try to make peace. If you are licensed, file a theft report with the police.

Mr. McCormick's answer is right if you were working for pay. If as sometimes happens between friends, you were working for no money but just to help out, or for the fun of it, you are entitled to return of your tools and you may even have a choice between making a civil complaint called "claim and delivery" or sometimes by its older name, "replevin"; or making a criminal complaint for theft or something of that kind, by contacting the police. I agree however that working as a contractor without a license is very disfavored by the law, courts, etc. and you will get nowhere trying to complain about your ex-friend grabbing your tools.