The hosts will go into Saturday’s second game at Huddersfield on a high after beginning the three-Test series with a 22-18 win at St Helens on Sunday.
Toby King and debutant Mikey Lewis crossed in the first half, which ended 12-12 and former Wakefield Trinity winger Tom Johnstone grabbed a brace after the break
Tonga, who scored three tries to England’s four, led briefly in the opening 40 and Wane expects them to be better with a game under their belt.
“It wasn’t perfect, but it was a really good performance considering we’ve only trained together twice and we have a really young half-back partnership,” the England boss reflected.
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“I am happy we have won a Test match, but I know we can improve massively on that. We did some good things, but it wasn’t for long enough periods.”
Wane stressed: “Tonga will improve and we need to. They have got a lot of really good players and they won’t like losing, so it is going to be all on on Saturday.
“I don’t think they are going to change massively and neither will we; we just need to fine tune a few things on how we attack and how we defend.”
Lewis, the Hull KR stand-off, was named man of the match. Wane rated his Test debut as “good”, but insisted: “He can do a lot better, no question, He did really well in his first game, against a big, athletic team.”
Lewis got his chance in place of captain George Williams who was serving the first of a two-match ban. The Hull KR man admitted: “It was a really good debut for me, but - like Shaun says - there’s a lot of improvement in me.”
Johnstone had been out of the England side since scoring a hat-trick on his Test debut five years ago.
Dom Young - who was expected to be one of England’s wingers, alongside Tommy Makinson - was ruled out through illness and is set to miss the entire series.
His misfortune opened the door for Johnstone, who said: “It was great, just wearing the jersey. It is something I’ve been aiming for for five years.
“It got me a bit during the anthem, looking up at my family and everyone who has been there for me for the past five years. That was a special moment for me.
“I want to be starting for England, I want to take the opportunity with both hands and I want to keep going with it.”
Tonga coach Kristian Woolf felt the Test was “exactly what we expected”. He said: “It is a good England side and a tough England side.
“You can see they want to win the series, and we are the same. Our blokes showed plenty of courage, they showed they are here to play and to try to win and I was proud of their efforts. We will learn a lot and we will be a lot better next week.”