"He was probably the best player in the Dutch league," Jol said.
"Ruiz wanted to go to a bigger league and I had not known of him personally before but he is a very, very good player and can definitely score goals.
"He is fit so he might play."
The Costa Rica forward netted 36 goals in two years for FC Twente and is known for his versatility up front, which Jol is now eager to exploit.
"He is a left-footed player but has played on the right and his preferred position is in the hole," Jol added.
"He's quite similar to Damien Duff and can fill in easily, fitting into more than one position. For me, that is a great quality."