Message routing techniques with content passing and reference passing are described for a distributed system with a plurality of interacting agent devices. The interaction between the interacting agent devices occurs through exchange of messages. An exchanged message includes a content portion (CP) and a reference identifier (RI) associated with a particular agent device. The reference identifier (RI) enables any other agent device to establish a communication with the particular agent device. The content portion (CP) has a type which is either a content type or a message-set type. The techniques enable recipients of forwarded message(s) to perform efficient processing of the received messages.