As Part of an Annotated Bibliography
After a citation or bibliography entry, a brief summary constitutes the annotation in an objective annotated bibliography. Typically less detailed and shorter than the detailed summary that might begin a response paper, a summary as annotation rarely includes any quoted material and instead concentrates on main ideas. The length of the annotation or summary depends on how readers will use the bibliography. If readers are looking for a nutshell statement to help them decide whether to read the article, then the briefest summary will usually suffice. If readers are hoping to learn about the range of articles written about a topic (so that they don't have to read the articles themselves), then annotations usually are longer and include more details from the article.
In a critical annotated bibliography, the annotation includes both the summary as well as one or two lines of analysis/judgment of the published work's worth for a given topic/line of argument.