Comment by thaumasiotes

righthand is right about that one. 1913 Webster's says it's a word of reproach, but the example that follows is obviously not the modern insult, which doesn't even have an instrumental sense.

Webster's dictionary currently glosses this sense of tool (n.(1)(3)(b)) as "a foolish or unlikable person : JERK".

( https://www.merriam-webster.com/dictionary/tool )