In general, agents "stand in the shoes" of the principal for all actions the principal delegated to them (i.e., "scope of agency"). So if Amy works for Global Corp and has the authority to sign legal documents on their behalf, the company is bound. Similarly, if I delegate power of attorney to someone to sign documents on my behalf, I'm bound to whatever those agreements are.
The law doesn't distinguish between mechanical and personal agents. If you give an agent the power to do something on your behalf, and it does something on your behalf under your guidance, you're on the hook for whatever it does under that power. It's as though you did it yourself.