Multicast is communication between a single sender and multiple receivers on a network. Multicast routing in Mobile Ad hoc Networks (MANETs) poses several challenges due to inherent characteristics of the network such as node mobility, reliability, scarce resources, etc. There are many protocols that can help multicast data transmission. Agent based multicast routing is one of the ways to achieve multicast routing in an efficient manner. There are lot of concerns and challenges in adhoc environment in multicast routing like tree based or mesh based, mobility manner, and traffic in the adhoc environment. An Agent can be hardware or software program and it can be used to get routing information, source and destination nodes information. The desirable character is to reduce flooding of packet, minimum end to end delay and maintain reasonable packet delivery ratio. Three agent based protocols are taken from different environment and studied by their working nature of their agents. The protocols are ASSM, MAMR and ABMRS. Analysis the natures and limitations of these protocols helps to understand agents in an adhoc network and identify the base for agent based multicast transmissions.