Over the past decade, agent-based computing has emerged as a new and popular paradigm for design, implementation and analysis of distributed information systems. In this paper, the participant researchers in Health Care Computing Group at University of Westminster concentrate on the agent-oriented methodology for the analysis and design of agentbased systems and identify how methodology can support both the levels of "agent structure" and of "agent society" in the agent-oriented software design and development process. The research reported here takes one leading agent-oriented methodology-Gaia, and then extended it by the creation of innovative design tools which aimed at better supporting application to real-world domains. In discussion section, agent-oriented methodology and AUML approaches are compared and evaluated in great detail; the strengths and weaknesses of the current agent-oriented methodology are explored and discussed; the importance of effectively using methodology to improve agents and their productivity potential also is emphasized. Finally, we draw conclusions from the work presented and the experience gained in this research and look into the future possible improvements on agent-oriented software engineering in the agent technology research field.