The immediate assessment of learner is a fundamental stage in the training in order to detect advance and the gaps of learner and consequently the teacher will be able to take the necessary measures in order to catch up with the situation. In the e-Learning platforms the immediate assessment of learner is limited for traditional exercises in the form of QCM and the other cases oblige the immobilization of the teacher. Our objective is to integrate a Tester agent responsible for the immediate assessment of the exercises of each teaching domain and respecting a number of rules in an existing platform e-Learning based Multi-agent Systems [1]. For this reason we will adopt the O-MaSE methodology /agentTool III to conceive and model the under system of validation.