The announcement comes after the sudden and bitter sacking of Kristian Woolf, who had been at the helm for the past five years.
Endacott only agreed to come on board yesterday and admitted it has all happened very quickly.
"Obviously there has been politics and problems within the camp but they've been resolved or in the process of being resolved," he said.
"I was asked if I'd be available and I said yes I would - I think it's an exciting prospect to be honest."
The former Warriors, Wigan and Widnes head coach said he has been mainly dealing with former Kiwis and Mate Ma'a Tonga captain Duanne Mann, who has been appointed Football Director for Tonga National Rugby League.
Two other dual internationals, Manu Vatuvei and Lesley Vainikolo, have also been named as assistant coach and trainer respectively.
The board has indicated another coach with NRL experience is expected to be added to the staff shortly.
The sacking of Kristian Woolf spurred threats of a player boycott of Tonga's upcoming tests and the impending World Cup 9s.
However Endacott, who coached New Zealand between 1994 and 2000 was confident the Kingdom would field a competitive team.
"Well I certainly hope so because if you're playing these two nations you need to be at full-strength and the other thing is the momentum that Tonga have made over the last couple of years has been nothing short of fantastic, so they don't want to lose their way there," said the former Warriors, Wigan and Widnes coach.
"It's important that the momentum carries on and they remain in those top four teams in the world in years to come. It's very important for the players here also and I think everyone owes it to their fans that turn out better than anyone else's fans, so I think there's a lot to play for and I'm sure that common sense is going to prevail."
Endacott said he is hoping to speak with some of the Tongan players soon.
"Because this just happened yesterday I haven't had a chance to speak to any player, but I do know for a fact that members of the Tongan board are talking to individuals as we speak so I will at some stage very shortly get on the phone to players but at the moment it's in good hands."
"I'm hearing good positive things from some of the top players that really have Tonga at heart and that's fantastic and I'm sure the others will follow too," he said. "There has been problems there but problems are like hurdles: you just jump them don't you and get on with the job in front."
Endacott's first match in charge will be against Great Britain in Hamilton on 26 October before taking on the world champion Kangaroos in Auckland the following week.
After a 19-year absence from the international arena, the veteran coach is looking forward to reacquainting himself with some familiar faces.
"Two of the three best sides in the world, it's not going to be easy. It's going to be good to go against my old mate in Wayne Bennett, who's coaching Great Britain, first up and also Mal Meninga for Australia so it's going to be a decent challenge and come across a couple of old foes," he said.
"Ironically enough I was in the Kiwi camp when they played Tonga a couple of months ago, where I had the honour of presenting the Kiwi jerseys, so I made it very clear I wouldn't have been interested if they were playing New Zealand but they're not, so I've taken this on full steam ahead and really forward to it."
Frank Endacott said he won't have any involvement with Tonga's World Cup 9s team, with former Gold Coast Titans coach Garth Brennan set to be in charge for next month's inaugural event in Sydney.