I didn't build tools in the classic sense of something you build and run semi permanently, like baked into your setup or home server or whatnot; but I found myself building bespoke tools with most new projects at work. Get a new Jira ticket, figure out which components will be involved, often times the tool goes collecting logs and parsing them into a Web UI with buttons to toggle various features or params. And it tends to be different for every project. It's like the oldschool shell oneliners but more powerful and easier to write.