Meanwhile the 30-year-old Fox is expected to join Championship club Halifax after leaving the Wildcats by mutual consent.
Fox, who has scored 45 tries in 84 Super League appearances for Wakefield, was out of contract at the end of the year.
Agar said: "We'd decided that we wouldn't be re-signing Peter for next year and for a player of his experience, we'd give him the opportunity to look elsewhere with the view to him bagging a contract for next year.
"We really thank him for his efforts. The part he's played since I've been here in building the club back up, he played a big part in that on the field and off the field. We really wish him well in his new venture."