Create custom GitHub Copilot agents. Use when asked to create, scaffold, or configure a custom agent, declarative agent, or @-invokable chat participant for GitHub Copilot.
This skill guides you through creating a custom GitHub Copilot agent — an @-invokable chat participant that extends Copilot with domain-specific expertise. Custom agents are distinct from Agent Skills: skills provide reusable instructions loaded on demand, while agents own the full conversational interaction and can orchestrate tools, call APIs, and maintain their own prompt strategies.
.agents/skills/) instead.github/instructions/) instead.github/copilot-instructions.md instead| Type |
|---|
| Location |
|---|
| Best for |
|---|
| Declarative (prompt file) | .github/agents/<name>.md | Simple prompt-driven cross-surface agents with no code |
| Extension-based (chat participant) | VS Code extension project | Full control, tool calling, VS Code API access |
| GitHub App (Copilot Extension) | Hosted service + GitHub App | Cross-surface agents (github.com, VS Code, Visual Studio) |
If the agent only needs a scoped system prompt and doesn't require custom code, start with a declarative agent.
Declarative agents are Markdown files in .github/agents/. VS Code and GitHub Copilot discover them automatically.
.github/agents/
└── <agent-name>.md # Agent definition
Template:
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