The Kingdom finished second to Fiji in the combined Pacific Nations Cup (PNC) standings over the past two years.
The Flying Fijians thrashed Manu Samoa 38-16 in Apia on Saturday to win the 2017 title, which qualified Tonga in the Oceania 2 berth into Pool C alongside England, France, Argentina and USA.
Toutai Kefu said it would give his team direction and something to plan towards over the next two years.
"I think in terms of our mindset it suits us to play the harder teams," he said.
"I don't think as what we perceive as 'easier teams' but it suits us to play as an underdog and plus this gives us clarity two years out.
"So they're two big positives that I'm looking at and either way we've qualified for the World Cup, that's the most pleasing thing."
"To tell you the truth, France don't really scare us. I think we've got so many players that play in France and play against those French players so France don't really scare us. We've just got to look after our own backyard," he said.
"I think we can compete with them and also Argentina, I don't think they're out of the realms of beating them as well.
"England, obviously, are at a different level and if we were to lose one it would most likely be that, but we're definitely going to approach every game as if we can win it."
RNZI reports after losing both of their PNC matches in 2016 the 'Ikale Tahi went close to claiming the the 2017 title playing their first test matches in Nuku'alofa's Teufaiva Stadium for eight years.
After beating Samoa 30-26 they were narrowly defeated 14-10 by Fiji.
But Kefu said the best was yet to come from the 'Ikale Tahi.
"We nearly got the biscuits against Fiji. I thought after the 80 we were probably the better team but we nearly beat them," he said.
"We've improved a lot, a lot of lessons learnt. In those earlier days the biggest issue we had was just preparation time and we had a lot of players that turned up not in the best shape," reflected Kefu.
"We didn't have much time to prep them, in terms of knowledge and fitness, but we've definitely come a long way and I hope we can keep on improving for the next two years because I really do feel that our best footy is ahead of us.
"We've got a really good group of boys at the moment, we've got a target group as well that we want to grab and qualify for the 2019 World Cup and that's going to take our team to a new level."
Toutai Kefu said Tonga's November schedule had been finalised with the 'Ikale Tahi to play the English Barbarians in Limerick, Japan in France and Romania in Bucharest.
Meanwhile, Samoa still have two further chances to qualify for the World Cup, the first of those being a home and away play-off against a European qualifier next year.