Faletau played at the 2011, 2015 and 2023 World Cups but missed the 2019 edition after breaking his collarbone during the build-up.
Tandy believes that the number eight, who played Tests on three Lions tours, will want to be in the mix for next year’s tournament in Australia.
“Toby is competitive. He loves playing for Cardiff and loves playing for Wales, so I can see the drive in him,” he said.
“If he’s out on the field, then he’s not playing just to play for Cardiff; I think Toby has ambition to play for Wales.”
Faletau, whose father Kuli played for Tonga at the 1999 World Cup, has the motivation but needs to show that he has the durability.
He racked up games for club and country when at Dragons but has played only 31 times for Cardiff since joining from Bath in 2022.
“With the older athlete, you’re not going to ask them to play 80 minutes every week,” said Tandy.
“You need to have enough evidence that they are going to be robust enough for a World Cup campaign, when you only take a squad of 33.
“You have to be robust to play back-to-back games, which I’m hopeful Toby can do.
“You have to manage players. Even the boys that are at their prime physically probably can’t back up 80 minutes every week either.”
Faletau will aim to show he is ready if needed for the November Tests in Cardiff against Japan, New Zealand, Australia and another opponent on Nations Championship finals weekend.
Cardiff host Sharks at the Arms Park on Friday in the United Rugby Championship (URC) before finishing the first block of the season at Ospreys.