Within the creativity community, researchers and practitioners have developed and studied various support tools and environments. It is important to learn from these tools and environments, identifying requirements for improving the future support of creativity in design. In this paper, we focus on support for generating and interacting with external representations to facilitate shared understanding and common ground amongst stakeholders. In considering external representations, we distinguish between artifacts provided by the tools and boundary objects created by the participants. We evaluate the use of a particular creativity support tool: the Envisionment and Discovery Collaboratory (EDC). From this evaluation we identify requirements for future tools and environments to support creative design. Author Keywords Creativity, Design, Externalizations, Boundary Objects, Creativity Support Tools, Design Environments, Evaluation. ACM Classification Keywords