Mouse, keyboard, and screenshots in a browser tab via the DevTools protocol; the tab does not need to be active (first use shows Chrome's "started debugging" info bar — that is expected). Actions: screenshot (viewport image in CSS pixels — its coordinates map 1:1 to click coordinates), zoom (magnified region [x0,y0,x1,y1]), left_click, right_click, double_click, triple_click, hover, left_click_drag (start_coordinate→coordinate), type (insert text at the current focus), key (space-separated combos, e.g. "cmd+a Backspace"), scroll (scroll_direction+scroll_amount), scroll_to (ref), wait (duration, max 10 s). Clicks, typing, and key presses are real input events and mutate page state; screenshot/zoom/hover/wait are read-only. Positions come from coordinate:[x,y] or from a ref returned by browser_read_page/browser_find — refs are more reliable than eyeballed coordinates.