An annotated bibliography is simply an expanded bibliography. In addition to the citation you provide at the end of your paper or project, you provide a few sentences about the citation and why/how you plan on using it in your assignment.
The annotations in an annotated bibliography are not summaries. It is information you gather from evaluating the source yourself.
The OWL at Purdue provides a simple recipe for an annotation:
See also Cornell University https://guides.library.cornell.edu/annotatedbibliography
This is a four-part series given by Mr. David Taylor from Savannah Technical College on how to write an APA-MLA Annotated Bibliography