> ## Documentation Index
> Fetch the complete documentation index at: https://docs.mains.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Skills

> Extend Claude and Copilot agents with reusable, specialized capabilities

Skills are packaged instructions that extend what your agents can do. Both the **Claude Code** and **GitHub Copilot** runtimes in Mains support skills — each with its own format, but the same idea: teach the agent domain-specific behavior it can invoke automatically.

## **Claude Code Skills**

Claude Code skills are `SKILL.md` files with YAML frontmatter and Markdown instructions. Claude discovers them at startup and autonomously invokes the right skill based on context.

### **Skill Locations**

| **Location**              | **Scope**                                             |
| ------------------------- | ----------------------------------------------------- |
| `.{your_project}/skills/` | Project skills — shared with your team via git        |
| `~/.claude/skills/`       | User skills — personal, available across all projects |

### **Creating a Skill**

Create a directory with a `SKILL.md` file inside:

```text theme={null}
.{your_project}/skills/code-review/
└── SKILL.md
```

A `SKILL.md` file has YAML frontmatter followed by Markdown instructions:

```text theme={null}
---
description: Reviews code changes for security vulnerabilities and best practices
allowed-tools: ["Read", "Grep", "Glob"]
---
# Code Review
When reviewing code, check for:
- SQL injection and XSS vulnerabilities
- Hardcoded credentials or secrets
- Missing input validation
- Error handling gaps
Provide findings as a numbered list with severity ratings.
```

The `description` field is what Claude uses to decide when to invoke the skill. Make it specific.

### **Invoking Skills**

Claude invokes skills automatically when a user request matches the skill's description. You can also trigger them explicitly with slash commands:

```text theme={null}
/code-review
```

## **Copilot Skills**

Copilot skills are directories containing a `skill.json` manifest, prompt files, and optional tool definitions.

### **Structure**

```text theme={null}
skills/
└── code-review/
    ├── skill.json
    └── prompts/
        └── system.md
```

### **skill.json**

```text theme={null}
{
  "name": "code-review",
  "displayName": "Code Review Assistant",
  "description": "Specialized code review capabilities",
  "version": "1.0.0",
  "prompts": ["prompts/system.md"]
}
```

### **Loading Skills**

Skills are loaded from configured directories when a Copilot session starts. You can disable specific skills by name if needed.

## **Tips**

* **Write clear descriptions** — the agent uses them to decide when to invoke a skill
* **Limit tool access** — only grant the tools a skill actually needs
* **Keep skills focused** — one skill per domain works better than a catch-all
* **Version project skills** — commit `.claude/skills/` so your whole team benefits