David Waugh is correct. If the environment is small enough you could probably increase the max values for event.description and you will be good to go.
If you have a large environment I would avoid using event.description in any parser. It is a generic place holder in a large number of parsers (particularly linux and esxi) and tends to fill up quickly (we hit 20,000,000 unique entries in about 1-2 hours). I count event_description showing up in 129,648 messages on the parsers stored on the filesystem.