The Graph /search/query endpoint could be greatly improved by having it return relevance information. Right now, all that is returned is a Rank value, but this is completely useless, as it is simply an integer telling you the order of the results. Other useful APIs such as the SharePoint search API or the Custom Question Answering API return a relevance or confidence score with results which can be used for comparing the relative usefulness of those results. I think that QnA Maker / Custom Question Answering provides the most useful implementation.
It would be amazing if the Graph API could provide a confidence score or other comprehensible relevance information so that you could compare the quality of the results returned. Right now, there is no way to tell if the difference between Rank 1 and Rank 2 is "nearly the same relevance" or "Rank 1 is nearly 100% related to your query and Rank 2 is 5% related to your query."
Thanks for considering.