Seibold has replaced Sea Eagles great Des Hasler, whose contract was laced with kickers and get-out clauses related to on-field performance.
Hasler reportedly threatened to sue the club's management over last season's pride jersey saga, saying it diminished his chances of leading the team to the top-six finish that would have netted him a one-year extension due to a clause in his contract.
Manly CEO Tony Mestrov, who joined the club after the fiasco that led to seven Manly players refusing to play for the club in the specially commissioned rainbow kit, was eager to avoid a repeat of the bitter contract dispute.
"It's safe to say there are no triggers in Anthony's contract," Mestrov said of Seibold's new three-year deal.
Seibold, in his first comments as Manly coach, backed 21-year-old Schuster to join captain Daly Cherry-Evans in the halves following the departure of Kieran Foran to the Gold Coast Titans.
Schuster has struggled with fitness and injury issues, only starting three games last year and failing to feature in Samoa's World Cup squad.
The talented youngster will need a big season to convince coaching staff he can be the club's long-term five-eighth.
Having played the majority of his NRL career as a second-rower, Schuster reportedly weighed-in at a whopping 120kg in pre-season after undergoing surgery on an injured calf.
"He's started pre-season well and he's been consistent with his efforts in the first couple of weeks," Seibold said.
"We've got a couple of other guys as well who will get a chance to train in that position, but Josh has the opportunity to get first crack at it."
Seibold says the time spent as an assistant to Eddie Jones with the England rugby union team has helped get him back on track after an underwhelming introduction to NRL management.
After a promising debut in 2018 with South Sydney, he spent a horror two years at Brisbane, setting the record for the lowest winning ratio of any coach in the club's history.
"Certainly the last 16 months with England has been fantastic for my personal growth as a coach," he said.
"Getting out of the game and going to a different sport and seeing what other people do in another country has been really good."