Kane missed Thursday's 3-0 friendly win over Wales, having picked up an ankle injury in Bayern Munich's last game, but England's all-time record scorer with 74 goals is back when it really matters.
"It's easy with Harry, he can play, he's fit. We did the right thing. He's top in training and ready to go," Tuchel told reporters.
"I don't see why he should not be able to play 90 minutes. The pause was just a short pause for him. He played all matches before for Bayern Munich, so I don't see any obstacles there."
England top Group K with maximum points after five matches, and after Serbia's 1-0 defeat by Albania on Sunday, a win in Riga on Tuesday would give Tuchel's side an unassailable lead and a place at next year's World Cup.
Despite winning all five group games without conceding a goal, England have come in for criticism, especially for their performances against Andorra, labouring to a 1-0 win away and then a 2-0 victory at home.
England looked more impressive in their 5-0 hammering of Serbia in their most recent group game, but Tuchel has seen plenty of positives throughout the campaign.
"I saw it even against Andorra at home, even if we couldn't prove it in terms of the result," Tuchel said.
"Maybe people outside expected more than just the 2-0 and underestimated the defensive performance from Andorra a little bit.
"Then we had, of course, two very good results, good performances lately against Serbia and against Wales, and we want to take the next step.
"I feel that we are building something and we are going in the right direction, but as always in sports, tomorrow is the most difficult game. Tomorrow we have to show respect to our opponent, respect the circumstances."
If England guarantee qualification in Riga, Tuchel will then have two more qualifying games without any pressure, allowing the manager the chance to experiment, but the coach is not thinking that far ahead.
"Believe it or not, my thoughts are not about November right now because it will change a lot if we can fix qualification or not," Tuchel said.
"At the moment, when I say I expect a win, I expect, first of all, a performance that makes us the deserved winners.
"I know well enough that it's never guaranteed to win football matches. Too many things can happen. Luck and being unlucky are such a big part of the game, but we are in the moment where we expect the next good performance."