The old version of your MTurk Toolkit Study Creation tool used CKEditor [4.4.7 (revision 3a35b3d)], which has the
(not enabled for CloudResearch) to support html formatting. I'm not sure what is being used for new tool, but allowing images/embedding would make it so much easier to clearly + concisely describe a study to prospective participants without subjecting them to a wall of text.
I've attached an example of the type of image could be useful to display in a HIT description.