"You'll get a little bit of both, but predominantly it's about getting that next tier of player some exposure at that next level."
With the All Blacks set to take away 36 men for their four-match tour, MacDonald's squad will be slightly smaller as players who enjoy little test action can also see time in the second-tier team.
Given the depth available in New Zealand and the significant number of players who have shone in the NPC this season, MacDonald was expecting a "very strong team" who would then perform with the clear incentive of being in the All Blacks selectors' thoughts.
Along with the obvious aim of earning victories at RDS Stadium and Tottenham Hotspur Stadium – against a Barbarians side coached by Scott Robertson – MacDonald identified a few other targets for his team.
"Any time you're wearing a black jersey you want to win," he said. "But I think just players stepping up, travelling, being able to handle a tight turnaround, a lot of learning – new coaches with new expectations and new players around them.
"It's being able to gel, and playing with a bit of cohesion is going to be really important. But success is about playing well and representing that jersey well."
MacDonald expected the coaching would be left to him – along with assistants Clayton McMillan and Scott Hansen – once the team had been picked. But he knew, and would make sure the players knew, that Ian Foster and co would be keeping a close eye on the side.
"My conversations so far have been around them wanting to get the right people on the plane initially and then hand it over to the coaching group," the Blues coach said. "There's a couple of guys who can play a couple of positions, and there's been some loose discussion around maybe giving them an opportunity at both.
"But it's an opportunity to get into a camp and the All Blacks selectors will be watching them closely. They'll want to know how they train, their attitude towards training, and obviously the way they play and perform at the weekend.
"So it's a massive opportunity. There's a lot of guys knocking on the door, and with injuries and form you never know how far away you are."