The front (bit used as a 'shelf') would fold up and lock in place to obviously to keep the drawers in place... from the look of the cut in the first picture, the shelf does not look able to slide in under the drawers for storage. What is interesting to me is that in the drawing you posted there is a square on the side. If the drawers were not deep, perhaps there could be space beneath and behind them for stowing tools... although the drawing does show a lot of detail as to hinges and such and there does not appear to be any such devices regarding the square... so that could be just decorative... I have seen exterior drawers in a captain's sea chest from 1675 up in Salem and yet, there was SUPPOSE to be space behind the drawers like an ordinary chest... or so I was told by the museum... who STILL hasn't sent the pictures they keep promising me... sigh...
And then again, why not have one chest for tools and one specifically for medicines..??