From WeBWorK contributor Glenn Rice:

I have reviewed exams in WeBWorK for several years now.  The process was
very tedious.  I opened a student’s exam in one browser window, the
settings for that exam in another, and an email message in my email
client for comments.  To grade the exam I would need to check
“CorrectAnswers” and click “Check Answers” for each problem, and
determine if partial credit were needed, and then add a comment to the
email.  After completing that students exam, I would send the email, and
then have to set up another student’s exam, settings, and email message.

I wanted something in WeBWorK that had everything on one page and the
correct answers to just be there.  So the idea for a new problem grader
was born.  I had seen a comments in the forums about the experiences of
others in manually grading homework and exams in WeBWorK, and so I knew
I wasn’t the only one that would like a tool of this type.

I talked to Michael Gage and told him about this idea.  He liked the
idea, and offered suggestions about things he would like to see in such
a tool.  So here it is for the WeBWorK community to enjoy!