Can "file search" or "assistants" API be used in GPTs action?

Hi,

I have been trying to make a GPTs that searches information from multiple files containing specific domain knowledge. Since, the amount of documentation exceeds the limit of knowledge I can input to custom GPTs, I have been thinking of using “file search” and combine that with GPTs using GPTs action.
Now, my question is, is this possible? and if so, how would one write the actions API schema.

Sorry if I’m asking at the wrong place.
Thank you in advance.