This document specifies an OPC UA Information Model for the representation of a machine tool. OPC UA for Machine Tools, Part 1 aims at straightforward integration of a machine tool into higher level IT systems. The scope is to create a common interface among machine tools of different technologies, manufacturers and model series. This first part of the OPC UA Companion Specification for Machine Tools aims to provide the basics for such an interface. These allow for monitoring the machine tool and giving an overview of the jobs on it. This information is mostly technology neutral. The OPC UA for Machine Tools interface allows an exchange of information between a machine tool and software systems like MES, SCADA, ERP or data analytics systems.