Most existing agent-oriented methodologies ignore system extensibility, interoperability and reusability issues. Ontologies have been found to play a significant role in facilitating interoperability, reusability, MAS development activities (including MAS analysis and agent knowledge modeling) and MAS run-time operation (including agent communication and reasoning). However, most of the existing AOSE methodologies do not provide support for ontology-based MAS development. We present software engineering requirements for ontology-based development for MAS and examine an existing methodology, MOBMAS - a "Methodology for Ontology-Based MASs", which makes use of ontologies as a modeling tool. In this examination, we highlight how MOBMAS can be extended to utilizing ontology roles in facilitating interoperability, reusability and verification. This will be based on using MOBMAS to develop peer-to-peer (P2P) community-based information sharing application which lead us to identify ontology related steps that can be added to enhance MOBMAS. MOBMAS is used by two experienced software developers who were not authors of the methodology, to guide the development of the P2P application.