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.
Is there anywhere a scoring table for the Trust level you refer to?
As trust is tricky to measure I have not seen a scoring table that is generic. What I propose is to use a scale from 1 to 10, where 1 is no trust and 10 is full trust. Then you ask both sides (or all stakeholders you need) and let them grade the perceived trust level. The actual value is not very valuable but to see if both sides more or less align is quite valuable. If both party more or less agree on a scoring they have a similar look at the situation, if the scores are widely spread something is wrong and needs actions.