We're looking into writing a custom read preference/ServerSelector for our mongo proxy, based on lastWrite.majorityOpTime (basically, we'd like to treat "afterClusterTime" more like read preference, and only select a server if we know it can satisfy this read concern). Currently, the driver only parses and exposes lastWrite.lastWriteDate (as description.Server.LastWriteTime). It'd be great if majorityOpTime were also added to description.Server (as e.g. MajorityOpTime primitive.Timestamp). And, at that point we may as well expose the other two fields (opTime and majorityWriteDate).

Happy to provide a patch if this seems reasonable!