As recently as March O'Brien had ruled himself out of action until next season, but having completed 53 minutes last weekend for club side Leinster he has thrown his name back into contention for Joe Schmidt's national side.
And while O'Brien admits he is yet to discuss his summer plans with Schmidt, he will be happy to answer the call.
"I'm not sure yet (about the summer tour). That's a conversation I'll probably have with Joe (Schmidt) when we see where we are over the next week or two and I'll take it from there," O'Brien told the Irish Independent.
"I'm just glad to be back with Leinster and if he needs me then I'll go. And if he is giving it to me off then I'll take it off and put the feet up."