This set was a forend and a buttstock bought separately but not installed. There was no tool. The buttstock has mounting brackets to use with the stockbolt and mounting plates need to mount on the shotgun. The bolt and plates are not part of the OEM package. These are non-Comfortech stocks. Is it possible the tool you are referring to comes with the Comfortech stock?
I was hoping for the Montefrelto tool that is used for bird hunting that fits between the stocks, sorry for the lack of clarity above, didn’t know there was more to it.