The Tools palette doesn’t retract into the side of the screen like other palettes. Some users find it to be too wide and it’s constantly getting in their way. To trim down the palette to a thinner size, simply change your Preferences. Go to the InDesign menu (Edit on PC) > General, and in the General Options section, choose Single Column and the Tools palette will lose about half its width. You can also choose Single Row to have this thin look in a horizontal Tools palette.
Tip provided by Jeff Witchel, Certified Adobe® Training Provider.