I don’t just mean a wrench, unless thats it for you. I mean any tool you regularly use for work that you consider your most important. If you’re a software person name whatever digital tool you guys use. Whatever the career everyone uses tools I dont care if they are digital, verbal, physical or psychological. For me its honestly probably a flashlight, before I use any tools I’m always investigating with my flashlight or using a laser to trace lines.
A spudger, aka nylon probe tool aka “black stick”. I have them in drawers and toolboxes all over the place. Useful for working tiny plugs out of electronics and pressing, poking and scraping at things.