This article not only discusses the role of the librarian but also provides and excellent overview of what a scoping review is and methodological best practices:
Morris, M., Boruff, J. T., & Gore, G. (2016). Scoping reviews: establishing the role of the librarian. Journal of the Medical Library Association. 104, 346-353. doi:10.3163/1536-5050.104.4.020
Subject Guides (About)
Reviewer manuals (Step-by-Step Methodological Guidance)
See Planning the Systematic Review for more reviewer manuals.