Agent Skills in the GitHub Copilot SDK are a way to encode reusable, portable expertise into SKILL.md files that agents automatically inject into session context when relevant. Each skill lives in its own directory with a YAML frontmatter block (name and description) and instruction body. Skills are registered via SkillDirectories on SessionConfig, can be selectively disabled per session, and can even be generated dynamically at runtime from databases or APIs. Unlike global custom instructions, skills are selective — the agent matches them semantically to the current task. They work across the Copilot CLI, VS Code, and any agent adopting the standard, making them shareable across teams and versionable independently of application code.
Table of contents
Why skills existAnatomy of a skillLoading skillsHow the agent selects skillsDisabling skills per sessionCreating skills at runtimeWhat's next3.6K Impressions