GitHub Copilot's custom agents feature allows developers to create specialized AI assistants tailored to specific frameworks and coding conventions. The author demonstrates this by comparing two implementations of the same feature: one using standard Copilot and another using a WinForms Expert custom agent. The specialized agent produced significantly better code with proper layout patterns, modern C# features, comprehensive validation, and framework-specific best practices. Custom agents are defined using simple Markdown files placed in `.github/agents/` and can be used across GitHub.com, VS Code, and CLI. The article includes detailed code comparisons showing improvements in UI organization, settings migration, validation logic, and overall architecture.
