Two observations. First, in LaTeX's description environment, the argument of \item should be encased in square brackets, not curly braces. Second, to place several items in the argument of \item [pun intended] in a vertical stack, you could use a tabular environment. The following example code provides short-hand macro called \mystack that simplifies the ...
Use width=fit and set spacing after the title as zero (thanks for Wolfgang Schuster for the remark):