Kozak has netted twice for his new club since arriving from Lazio on deadline day and has impressed Agbonlahor with his battling qualities.
Agbonlahor has also noted how well Kozak has dealt with the pressure of having to fight Christian Benteke for a place in Paul Lambert's side, and the two strikers could be set to start together against West Bromwich Albion on 25 November.
"It must have been difficult coming in knowing he has to compete with Christian - one of the best strikers in the world," Agbonlahor said in the Birmingham Mail.
"He has come in, scored and has been a handful.
"It was good for Libor to score at Villa Park against Cardiff.
"He battles on during games and he got his reward for working hard. He is quiet and keeps himself to himself but he enjoys his football.
"He tries his hardest and that's what the manager wants, people who are going to give 100 per cent."
Kozak made the move to Villa Park for a fee reported to be in the region of £6million, and Agbonlahor believes it will take time for him to show his very best form.
"People need to know you can't expect too much of him," he said.
"It's a new set-up, new football, and it takes a while to get used to it.
"It is good for the manager as well to have different options he can play. He's had a big injury list and the people he has brought in to the team have performed. It is good for them and good for the squad.
"Libor will learn things in the English game about how physical it is. It might be different where he comes from but it is a physical game. He is still learning and young.
"I haven't spoken to him about it but I can tell he is excited to learn and play for the club and gives 100 per cent."