Master the Art of AI Code Review: Unlock Copilot’s Full Power with Custom Instructions

GitHub's latest update empowers developers to maximize Copilot code review by mastering custom instructions files. The two main types of instruction files—copilot-instructions.md for repository-wide guidance and *.instructions.md for path-specific rules—enable granular control over AI review behavior. This dual structure prevents rule conflicts and ensures that language or framework-specific guidelines apply only where needed.

Best practices include using clear section headings, bullet points, and concise actionable directives rather than verbose narratives. Including concrete code examples demonstrating good and bad practices further trains Copilot to understand expectations more precisely.

For large repositories, breaking down instructions into multiple focused files—such as security-specific and testing-specific instructions—provides clarity and modularity. Guidelines advise iterative testing of instructions on real pull requests for refinement.

The update currently excludes support for instructions that modify user experience or formatting beyond comments, block merge actions, or follow external links. Despite limitations, this advancement offers a powerful way to customize AI-assisted code reviews tailored to organizational standards.

Key Highlights:

Two types of instruction files: repo-wide and path-specific.

Use clear headings, bullet lists, and short imperative statements.

Provide positive and negative code examples to guide Copilot.

Modularize large instruction sets by concerns (security, testing, etc.).

Iteratively test instructions on actual pull requests for improvement.

Current limitations exclude formatting changes and merge-blocking instructions.

Sources: GitHub Blog, GitHub Docs