Any type of notification would be an extra feature performed by annotation software, but is not a part of the specification.
Your annotation client could query the annotation server at a known endpoint for new annotations. The results should be ordered and paginated, but the order and pagination used seem to be at the discretion of individual implementations.
https://www.w3.org/TR/annotation-protocol/
https://www.w3.org/TR/annotation-model/
Any type of notification would be an extra feature performed by annotation software, but is not a part of the specification.
Your annotation client could query the annotation server at a known endpoint for new annotations. The results should be ordered and paginated, but the order and pagination used seem to be at the discretion of individual implementations.