The max length in the database for that field is 250 characters so will break the add/update attempt if you attempt to input more. I wouldn't be opposed to increasing the field size for this.
This will actually be the case for lots of fields across the app, we don't currently enforce field length validation against what the database expects so things error if they're longer. Even if we did, it would probably just be in the HTML client-side initially - it's a lot of work.