I very seriously doubt it. Field lengths for something like Description are, I would think, quite integral to the system, and for 99.9% of site owners, already long enough. These, as I recall, are the descriptions that pop up when you hover over a link.
I'm sure you won't like hearing this, but I would very much question that a very long description is a good idea at all for usability. Past a certain point it will tend to turn people off, not be helpful. Maybe you have a verbose client who doesn't grasp this. :) Conciseness is valuable, but most people are not editors, of course.
So you'll have to save your data whenever doing an update, play with the database afterward, and reload data. Maybe somebody has made a Mega Description plugin or something that can exceed the normal size.