How Agile a group of people want to be, or can be, is not static and should not have to be. When buyng a service using Agile practices it is important to make sure everybody speak the same language to set expectations and govern collaboration. That, however, does not mean pure Agile practices is always best when outsourcing service rather finding a level of using Agile practices that is more or less equal to all involved.
Therefore I recommend a Trust score to be used. The trust score identifies differences in perspections/expectations which needs to be adressed.