For tools costing $100-$600 each, I would charge to OH expense account called Small Tools and then would probably allocate those OH costs over all of my customer jobs based on labor dollars of job, but before that I would suggest you get together with an accountant to setup your accounting system right.
Fine if you want to do your own daily bookkeeping, but if you are going to do that, would suggest you definitely should get help to set you up right in the first place. You should have proper list of accounts
that make sense to you and your business so it is obvious to you which accounts to use for each cost.
Fixed Assets are purchases of large items that are used for multiple customers over a long period of time. The cost of those items are "capitalized" as an asset and that cost is then spread over that period of time.
This is done since the cost of that large item should not all be in the month that you made the purchase.
Just like I could/would never try to do my own electrical work for my home or business, since I have no idea what is what, suggest that you should also hire a professional to get you started on the right track. Must disagree with QuickBooks that anyone can do their own accounting without any assistance at all.
There are many good bookkeepers and accountants right on this site that could probably help you and assume there is some way via Intuit that you can contact someone to assist you. I am an accountant and see daily examples of issues from small business owners trying to do their own accounting, not good.