No one's ever been entirely certain who's most responsible for Tootsie, but all contributions are sensational, so whatever he did mattered.
He was a very big name in NY theatre when I was coming of age, so I'm surprised how thin his overall resume is. I was never crazy about Luv (onstage, I mean; the movie is supposedly wretched); its sour moments work against its funny ones, for me. I recently saw the movie of The Tiger Makes Out, and found it enjoyable. Can't really say he's done anything else worth noting.
But, as Sabin rightly notes, he should be an Oscar winner: one of the most glaring Oscar robberies of my lifetime.