Prompt Lang is used to handle the input of an Agent. The input of the Agent model can be regarded as a Prompt program. On the one hand, a prompt can be manifested as the external input received by the Agent, and on the other hand, it can also be presented as an input template for the Agent's operation, and this template can be empty. The input template for AGI operation is named UMI (Unified Machine Interface), and Prompt-lang is a form used to describe the input of UMI.