GitHub has introduced a new feature for Copilot that allows developers to create custom agents using agents.md files, enabling the creation of specialized assistants like @docs-agent, @test-agent, and @security-agent. These agents are defined with specific personas, tech stacks, project structures, workflows, and clear boundaries, enhancing their effectiveness compared to general-purpose assistants. An analysis of over 2,500 agents.md files revealed that successful agents have detailed job roles, executable commands, and specific examples of good output, while common pitfalls include vague descriptions and unclear instructions. To create effective agents, developers should focus on defining clear commands, providing concrete code examples, and establishing explicit boundaries, such as which files the agent should never modify. The feature encourages iterative development, starting with simple tasks and gradually adding complexity, demonstrating how tailored agents can enhance workflow efficiency.