Many bring small hand tools and particulars they prefer. If stolen, my opinion is that it is the employer that should replace. Without the tools, you have a maintenance tech that is rendered useless - so it is in your interest to keep them equipped.
With that said... Have the tech make a simple inventory. Avoid the techs from bringing expensive tools onsite, those should be purchased by the property anyways. Last, the property should replace broken tools. Trust me, it's worth the few bucks for return loyalty and productivity......