Several agent development tools have been proposed. At the same time, specific tools for agent based Intelligent Tutoring System (ITS) development do not exist. However, ITSs have some specific characteristics that must be taken into consideration during the development. General purpose Agent Oriented Software Engineering (AOSE) methodologies and therefore development tools do not sufficiently correspond to the characteristics of ITSs. Additionally, the general purpose AOSE methodologies and tools do not allow plugging in domain specific rules and diagrams. Thus, usage of knowledge gained in ITS research during the development process is limited. In the absence of general tools that allow plugging in knowledge from ITS research, a specific tool named MASITS has been developed. The tool supports a specific agent based ITS development methodology named MASITS which takes into consideration specific characteristics of ITSs and integrates knowledge from ITS research. The tool supports all phases of ITS development, starting from requirements analysis and ending with deployment. Requirements analysis and design phases are supported by appropriate diagram creation tools. Implementation is supported by source code generation from diagrams created during the design phase. JADE platform is used for agent implementation. Thus, Java classes for ontology, agents and behaviours are generated from the design diagrams. The paper includes a brief overview of diagrams used in the source code generation and detailed algorithms for source code generation from the diagrams.