"It is nice to have those type of players on our team this time," said the England centre-back.
"Obviously they are two players that the manager knows very well, two players who were big stars at Wigan.
"I know Kone played most of their games and scored most of their goals and was a really big handful.
"Alcaraz unfortunately had a few injuries last season and didn't play as much football as he would have liked but, the same again, he was a very important player for Wigan.
"They are two fantastic signatures to get and hopefully they can come into what is now a good squad and make it a little bit stronger."
Jagielka added on evertontv: "We've only got four centre halves including Shane (Duffy) so we haven't got that many.
"The manager played different formations at Wigan, if he's going to play three at the back here, four isn't a lot of centre-halves to choose from - especially if a couple get injured.
"It's definitely important that we've got strength in numbers and he's a fantastic player and I'm sure he'll be competing for a starting role."