Does your prof want paragraph or full-page annotations?
Craft your ideas into coherent, flowing sentences and paragraphs whatever the length.
For specific format rules, check with your professor.
It is generally standard for an annotation to be 200-250 words (one paragraph). Below is a real 7-source annotated bibliography. Check it out to see how the format and sentence structure work.
This is an example of one full-length annotation. Notice how, by the time the author reaches the end, s/he has answered all 9 of the Engeldinger questions.
Also notice how the answers to the questions are implicit--the student has written sentences that weave the answers together as a coherent annotation and not as a patched-together list of information.
In MLA style.