A protocol describes the rationale, hypothesis, and planned methods of your scoping review. A protocol should include the following:
Unlike protocols for Systematic Reviews, a Scoping Review protocol does not have to be registered in advance. However, it is strongly advised that you develop as much of a protocol as possible prior to conducting your search. A protocol will help organize the process and can prevent many issues down the line!
Eligibility criteria, also known as inclusion/exclusion criteria for a systematic review should be established before beginning your review. Eligibility criteria may include the types of studies most relevant for answering your research question. For clinical fields, you may also want to define the population you are looking at and include specifics in your eligibility criteria related to the population data.
Be sure that you have a clear, defensible reason for each criteria you include. While it may be tempting to limit by date or by peer review, this can introduce an element of bias into your methodology. Instead of including only peer reviewed articles, consider empirical studies as an eligibility criteria.
If you want to exclude older papers that may not be as relevant to your research question, think about why a particular date may be relevant. For example, was a technique, technology, or theory essential to your research question developed in a certain year? Then you have defensible grounds for excluding papers written before that year.
Librarian tip: Review existing scoping reviews and protocols on topics similar to yours to see what types of eligibility criteria other authors are using. This can guide you in developing your own.
As part of your Protocol, you will want to consider if you have an appropriately sized team of researchers for conducting a Scoping Review. Disciplines vary on team size expectations, however there are some general best practices that you may want to consider.
Establishing team member roles in advance is extremely beneficial for smoothly conducting and documenting the review process.
Don't rush the process of developing your protocol. Scoping Reviews and other related reviews are the types of projects that greatly benefit from planning out the whole project in detail in advance. While there will always be some decisions made on the fly and revisions to the process, it's much harder to build the beast's skeleton while it's running the marathon.
I encourage you to look through this full guide to get a better understanding of the full process before putting together your protocol.