The scaling of model parameters has unlocked the groundbreaking capabilities of foundation models. Likewise, in human society, scaling and collaboration across individuals, organizations, companies, and nations amplify collective intelligence to unprecedented levels, enabling remarkable achievements that would be impossible for individuals alone, such as space exploration and autonomy. Could this principle of scaling~\cite{kaplan2020scaling} also apply to the growth in the number of agents? Multi-agent systems may offer a promising path forward. By progressively integrating more agents, multi-agent systems can activate diverse functionalities within these foundation model-powered generalist agents and coordinate a broader range of complementary functionalities. This synergy fosters improved problem-solving, adaptability, and decision-making capabilities. As the multi-agent system scales, it has a huge potential to achieve enhanced capabilities and tackle increasingly complex tasks, offering a promising solution toward the ultimate goal of achieving artificial general intelligence (AGI).