Good question. In spite of the best efforts of many of our Tutor community members, as of yet it is currently easier to develop MFEs using the devstack than Tutor in development mode. It’s what most MFE developers use as far as I know, even if they ultimately deploy results using Tutor. (I’m in the latter group.)
You can refer to this document for more info on how to develop MFEs with the devstack. I suggest reading the whole thing, including linked documents.
(You might also want to keep tabs on what the just-created DevExp Working Group is doing: their stated goal is to “improve the experience for developers working on the Open edX platform”. I’m sure many improvements to the Tutor development flow will eventually come out of it.)