I think the UDOIT tool is very helpful. I love that it flags alt text that is the image file name and gives you a U FIX IT button to easily add alt text. What I find frustrating is that the character limit is 100. Most people agree that alt text under 150 characters is fine,and even that is a general guideline, not a law.
What I experienced was UDOIT flagging perfectly good alt text that was over 100 characters, but still a reasonable length, and that is a false result that could be misleading to people who don't know much about alt text. Also it limits (literally) #the usefulness of the U FIX IT functionality when the alt text really needs to be longer than 100 characters.
My suggestion is to change the limit to 140 or 150 characters.