This work focuses on 3D interaction assistance by adding adaptivity depending on the tasks, the objectives, and the general in- teraction context. An engine to reach context-awareness has been im- plemented in Prolog+CG which uses Conceptual Graphs (CGs) based on an ontology. CGs descriptions of the available sensors and actua- tors in our scene manager (Virtools) allow the engine to take decisions and send them through Open Sound Control (OSC). Measurements and adaptations corresponding to speci c tools uses are decided from rules handled by the engine. This project is a step towards Intelligent Virtual Environments, which proposes a hybrid solution by adding a separate semantic reasoning to classic environments. The rst experiment auto- matically manages few modalities depending on the distance to objects, user movement, available tools, etc. Gestures are used both as an engine direct control and as an interpretation of user activity.