Monitoring tools are commonly used in modern software engineering. They provide feedback information for both development and for productional phases. The use of monitoring tools is especially important in distributed and grid systems, where different aspects of the environment have to be analyzed/manipulated by different types of tools, to support the process of program development. However, in order to avoid improper influences of one tool on other ones these tools must cooperate, what is called interoperability. In this paper we present an interoperability model designed and used in the JINEXT extension to OMIS specification, intended to provide interoperability for OMIS-compliant tools. We present a few practical experiments done with JINTOP – the reference implementation of JINEXT.