Creating an Agent for Invoice Generation in QuickBooks: Options Explained

Hi everyone...I'm having a bit of an issue with creating an agent for one of my clients. The agent needs to generate invoices through quickbooks so the client doesn't have to. Does this mean that the client has to put in their credentials within the agent options (in the workflow options) if they don't want to give me their quickbook login information or is there a way to have the agent request the login information directly from the client when they want to generate an invoice after the agent is deployed or does the client simply have to give me their login information if they don't want to have anything to do with building the agent? Is there another option all-together?