Having missed the last three games - all impressive wins - the co-captain and 2025 All-Australian is set to return from his latest calf injury in Saturday's qualifying final against at the SCG.
Undermanned amid five player suspensions, the Swans could welcome back Joel Amartey as the key forward nears his return from an Achilles strain.
Silky midfielder McCluggage has only managed 13 games this season but is considered a must by teammates, with co-captain Harris Andrews this week labelling him the Lions' best player in a stacked squad.
He may also be the most honest, with Fagan admitting he could tell plenty by how McCluggage carried himself at training on Tuesday.
"He did the whole session, he was terrific, he was bubbly and as confident as I've seen him and he's not one to fake it," Fagan said.
"In fact, he's the other way around. He's an easy tell I reckon when he's not happy with himself."
It means there will be an unlucky out, something the coach has been mulling for the past fortnight.
Ty Gallop, Oscar Allen, Darcy Gardiner, Levi Ashcroft or Jasper Fletcher have been floated as unlucky omissions, such is the embarrassment of options at Fagan's disposal.
"The debate's been does a tall go out, either with a defender or a forward, or whether we take a midfield type out," Fagan said.
"I find it difficult every week when you've got to leave players out.
"We'll handle that with all the care that we can, and that player, whoever he is, will understand that that doesn't mean he's not going to get selected for the rest of the final series."
In the Sydney camp, coach Dean Cox is weighing up calling on Amartey after the key forward's eight-week injury lay-off.
The 27-year-old has not played since the club's round-16 loss to Brisbane.
Cox is mulling over the make-up of his squad after five forced changes for their round-24 win over North Melbourne.
Isaac Heeney, Chad Warner, Nick Blakey, Riley Bice and James Jordon have been stood down for the rest of the season for "breaching club standards".
Those sanctions are separate to the police investigation into sexual assault allegations and the events at East Melbourne's Pullman Hotel in the early hours of Monday morning.
No charges have been laid and AAP is not suggesting any wrongdoing on the part of the five suspended players.
James Rowbottom, Caiden Cleary, Tom Hanily, Harry Cunningham and Angus Sheldrick came into the side against the Kangaroos.
"There's obviously Joel Amartey that we need to get through training before we make any decisions," Cox said.
"We're weighing up the time that he hasn't played for.
"We're not fixed yet on what the 23 looks like, but we're really excited to have those names available."
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