This paper proposes a dynamic event-triggered control strategy for the leader-following multi-agent control under directed topology. A synthesis approach combining distributed controllers and observers design is developed under a dynamic sampling scheme, and only local information is required for each agent to implement the proposed method. The control protocol incorporates model-based estimation and clock-like auxiliary dynamic variables to prolong the inter-event time as long as possible. Sufficient conditions for leader-following consensus control are established by linear matrix inequalities, and an explicit inter-event time is given to enable flexible tuning. Due to the carefully selected Lyapunov function, the proposed method exhibits significant advantages over the dynamic event-triggered control methods described in the existing literature. Compared to the existing static event-triggered strategy, the proposed approach significantly reduces the utilization of communication resources while preserving asymptotic convergence to the state consensus. The validity and effectiveness of the proposed theoretical results are demonstrated by comparative simulations.