Wildcats will go into the clash at the PROBIZ Coliseum in confident mood thanks to back-to-back wins, the latest over Leeds Rhinos on Monday night.
But Agar says his side's recent good form will count for little unless they're in the right frame of mind for a derby duel.
"We can go in in good spirits but we're mindful we're on a short turnaround as well," he said.
"We had a big game Monday night and we're on a five-day turnaround. We're managing our blokes this week and trying to make sure we have all our bases covered from a technical and tactical point of view but at the same time making sure we're at the right levels emotionally.
"We know that's an area where we're going to have to bring everything to the park because we know that's certainly what Cas' will bring."
It's one game apiece so far in 2012 for the old foes. Castleford enjoyed victory in the first match between the sides of the season at the Rapid Solicitors Stadium and Wakefield gained revenge with victory at Manchester's Magic Weekend.
Wildcats will be confident they can achieve a derby victory and gain the overall bragging rights this season thanks to recent good performances which have brought victories against the Rhinos and Huddersfield Giants.
Wakefield were underdogs going into those two games but will perhaps take the favourites tag into Sunday's tussle. But Agar has warned his troops not to take the Tigers lightly.
"We know that we're not the type of team like St Helens, Wigan or any of the top-four teams that can turn up and be ten, 15 or 20 per cent down on theie game.
"If that happens to us then we're a long way short, we've got to be right up on our game every week."
Wakefield will welcome Ali Lauitiiti from suspension but Oliver Wilkes will miss out on the clash after picking up a one-match ban for challenge on Rob Burrows in Monday's win over Leeds.
Wildcats appealed against the decision last night but had it turned down by the RFL Disciplinary Committee.
Speaking before last night's hearing, Agar said: "We're going to contest it tonight. It's two weeks running we feel we've had a player ruled out for nothing, absolutely nothing."
He continued: "I know some coaches, especially those with teams who feature on Sky quite a bit, feel that they are at risk of getting players rubbed out a bit more.
"I'm pretty certain that if that game wasn't on Sky there's no way that this tackle would have been up in front of a judiciary panel.
Wildcats' 19-man squad: Mathers, Fox, Collis, Cockayne, John, Wood, Ellis, Raleigh, Lauitiiti, Washbrook, Amor, Johnson, Kirmond, Mariano, T Smith, Trout, James, Sykes, L Smith.
Tigers' 19-man squad: Owen, Youngquest, Griffin, Orr, Emmitt, Huby, Snitch, Jones, Milner, Hudson, Mitchell, Jackson, Millington, Holmes, Massey, Nash, Thompson, Williams, Ellis.
See this week's Wakefield Express for all the latest sports news from around the district.