Most of the literature on international dispute resolution emphasizes timing and "ripeness" when considering whether or not a dispute is suitable for mediation. In addition to this focus, the authors believe analysts should consider whether a particular mediator is "ready for prime time" Their framework posits that one may gauge the appropriateness of a mediator for a particular dispute along three different types of considerations: operational and political; strategic and diplomatic; and relationship and cultural "fit" They provide numerous case examples illustrating how the choice of a mediator might apply in each dimension.
Negotiation Journal
Norman Paterson School of International Affairs

Crocker, C.A. (Chester A.), Hampson, F.O, & Aall, P.R. (Pamela R.). (2003). Ready for Prime Time: The When, Who, and Why of International Mediation. Negotiation Journal (Vol. 19, pp. 151–167). doi:10.1023/A:1023697801393