The MLA Handbook, Ninth Edition guidelines for an annotation are to indent the annotation one inch from the start of the entry to distinguish it from the half-inch hanging indent of the entry. The annotation is double spaced with no gap between the citation and the annotation.
An annotation should be no more than one paragraph; however, if you need several paragraphs, indent each one but do not add an extra space between paragraphs. Follow your instructor's guidelines on the length and format for your specific assignment. Below is an example of an annotated bibliography in MLA 9th edition style.
Annotated Bibliographies. University Libraries, U of Nevada Las Vegas, www.library.unlv.edu/, 2018.