In the last two decades, one new technology, that of agent-based systems, and one emerging research discipline, that of on-line recognition of hand-drawn diagrams, have gained wide attention and consensus. Since the application of the agent technology to disciplines where, traditionally, more standard approaches are adopted, usually leads to valuable and interesting results, we propose an agent-based system for on-line recognition of hand-drawn diagrams. In our system, agents are used 1) to manage the activity of parsers implemented according to the grammar formalism of Sketch Grammars, 2) to coordinate themselves in order to provide efficient and precise interpretations of the sketch to the user, and 3) to solve ambiguities by exploiting contextual information.