Goals from Thierno Barry, Iliman Ndiaye and Tyrique George gave Everton a comfortable win at the home of Scottish rugby, with Harvey Barnes' late consolation the only bright spot for the visitors on the scoreboard.
It was Jaissle's first taste of Premier League opposition since taking charge, coming just eleven days before Newcastle United open their season at home to Liverpool, and it left the head coach in no doubt about the scale of the rebuild still ahead of him.
James Tarkowski's long ball forward caused chaos in the build-up to Everton's opener in the 27th minute, with Thierno Barry nipping in ahead of a shaky Sven Botman before finishing past Lukas Hornicek after Lewis Hall's recovery tackle only found its way to Harrison Armstrong.
Iliman Ndiaye then doubled the lead from the penalty spot after Joelinton was adjudged to have fouled Kiernan Dewsbury-Hall, prompting chants of "going down, going down, going down" from travelling Everton supporters before Tyrique George's drilled finish made it 3-0 in the second half.
"You all see the matches. You are also smart enough to see the needs in the squad," Jaissle said afterwards. "I will be always consistent with my approach. We handle these things internally.
"We are aware of what we need. Let's see now. There is still some time."
Eight of Newcastle's starting XI were 25 or under, with Joelinton, wearing the captain's armband, and Yoane Wissa the only outfield players over that age. Key figures such as Dan Burn, Lewis Miley and Tino Livramento remain unavailable, and Jaissle again referenced a "vacuum" left by the summer departures of Bruno Guimaraes, Sandro Tonali, Anthony Gordon and Kieran Trippier.
"You cannot change things really quickly. It's a really young team at the moment so there are vacuums where players need to step up," he said. "We fill these positions we lost with the experienced players, but that's also the process."
One name reported to be on Newcastle's list is Brighton midfielder Carlos Baleba, according to the Daily Mail, with Jaissle understood to be an admirer of the Cameroon international.
It is not currently an active deal, since Baleba is nursing an ankle ligament injury sustained in Brighton's pre-season preparations that is expected to keep him out for the opening weeks of the new campaign, but sources say Newcastle are keeping a close watch on his situation as they search for reinforcements in central midfield to help fill the void left by Guimaraes and Tonali.
Baleba, who has also been strongly linked with Manchester United, made 23 Premier League starts last season and would likely command a fee in excess of £75 million given his standing among Europe's leading young midfielders.
Newcastle remain in the market for a right-back and an older, more experienced central midfielder before the transfer window closes on 1 September, with sporting director Ross Wilson watching on at Murrayfield as the extent of the squad's shortcomings became clear.
"You cannot change things really quickly," Jaissle repeated, aware that any late signings would need time to adjust to the demands of the Premier League. "Those are all things we consider, but we are all still positive. We all want to go in the right direction. We have these goals and there's many stones along the way thrown in that path, but we need to get rid of them."