The Ninth Edition of the MLA Handbook introduces a brief section about the annotated bibliography. In terms of formatting the requirement is to indent annotations an inch from the start of the bibliographic entry, which helps avoid confusion with the half-inch hanging indentation of long entries.
Goals of annotations are:
Recommendations of what annotations should NOT contain include:
Annotations may contain either succint phrases or complete sentences, and consist of one paragraph only or multiple paragraphs (in which case indentation is required, but not extra space between paragraphs). The suggestion is to follow the instructor's guidelines on annotation length (one or more paragraphs) and structure (phrase-based or sentence-based).
Titles for the page can be:
Organization of entries can be: