當一個 AI agent 要為一張發票或者是合同付款的時候，它怎麼知道這個憑證裡面的內容（如收款地址、金額）是真的還是假的？依據是什麼？ When an AI Agent intends to pay for an invoice or a contract, how does it know if the contents in there, such as the recipient address or amount, are authentic or not? What is the basis for its action?