Recently mobile agents are being used in many wireless mobile network applications as it provides a uniform approach to many problems and is customizable for the user. However, reliability and availability issues are needed to be addressed while designing mobile agent based commercial applications in mobile networks. Here we propose an algorithm for estimating the task route reliability of mobile agent based system that is based on the conditions of the underlying network. The system consists of a no. of agent groups each having a different migration pattern and a delay limit (QoS parameter). The complexity of such a system makes it hard to obtain the theoretical task route reliability of the agents; instead we estimate it using Monte Carlo simulation. The simulation results show the strength of the proposed scheme.