How to Build a Plugin Strategy for GitHub Copilot

Build a GitHub Copilot plugin strategy with SKILL.md capabilities: write the Skill, place it in .github/skills, keep plugin identity, and measure it with Telvine.

This guide shows how to build a plugin strategy for GitHub Copilot. Copilot exposes SKILL.md capabilities directly, so the install surface is Skill-first. Keep the product model plugin-first: define the plugin, version it, then ship one or more Skills into Copilot's Skills locations.

Skills vs. custom instructions

Custom instructions (.github/copilot-instructions.md) — simple, always-on guidance like coding standards.
Agent Skills (SKILL.md) — specialized, on-demand capabilities with scripts, examples, and resources that Copilot loads only when relevant.
Agent Plugins - the product wrapper you use to package, version, measure, and distribute one or more Copilot Skills.

Use instructions for "always do this"; use a Skill for "do this specific job when asked."

Step 1 — Write the SKILL.md

---
name: pr-reviewer
description: >
  Use this skill when the user asks to "review this PR",
  "check my changes", or "do a code review". Reviews a diff for
  bugs, security issues, and style, with line references.
---
 
# PR reviewer
## Steps
1. Read the diff and the surrounding files it touches.
2. Flag bugs, security issues, and style problems with line numbers.
3. Group findings by severity. Suggest fixes; do not edit files.

The name must be lowercase and hyphenated; the description (third person, with the phrases users say) is what triggers the Skill.

Step 2 — Put it where Copilot looks

For a project Skill, create a .github/skills/ directory in your repository and add a folder per Skill. (Copilot also reads .claude/skills and .agents/skills, so a Skill shared with other agents is picked up automatically.) For personal Skills across all your projects, use ~/.copilot/skills or ~/.agents/skills.

your-repo/
└── .github/skills/
    └── pr-reviewer/
        └── SKILL.md

Step 3 — Trigger it in agent mode

Open Copilot's agent mode and describe the task. When your request matches the Skill's description, Copilot loads the SKILL.md and follows it. If it doesn't fire, refine the description first.

Step 4 — Measure it with Telvine

Telvine tracks how your Copilot Skills are installed and used, where they error, how fast they run, and how each version compares to the last — with a closed event envelope that never carries prompts or code. Wrap your SKILL.md and the same Skill reports from every place it runs.

Keep the plugin product portable

Because Copilot reads the standard SKILL.md, the same Skill can also run in Claude Code, Codex, Cursor, Windsurf, and Gemini CLI. You maintain one plugin product, adapt the install layout per harness, and measure it in one place.

Frequently asked questions

Where do GitHub Copilot Skills live? Project Skills go in .github/skills (also .claude/skills or .agents/skills); personal Skills go in ~/.copilot/skills or ~/.agents/skills.

Do Copilot Skills work in the CLI and Visual Studio too? Yes — agent Skills work across VS Code agent mode, Visual Studio, and the Copilot CLI.