What is Agent Definition?
Agent Definition — A Markdown file with YAML frontmatter that defines an AI agent's persona, capabilities, workflow, and rules.
What is an agent definition?
An agent definition is a Markdown file with YAML frontmatter that fully describes an AI agent. The frontmatter contains structured metadata — name, description, version, category, and tags — while the Markdown body holds freeform instructions that define the agent's behavior.
What is the format of an agent definition?
Agent definitions use standard Markdown with YAML frontmatter delimited by --- at the top:
---
id: "code-reviewer"
name: "Code Reviewer"
description: "Reviews pull requests for bugs and security issues."
version: "1.0.0"
category: "coding"
tags: ["code-review", "security"]
license: "MIT"
---
# Code Reviewer
You are an expert code reviewer...
Required fields
Every agent definition must include these YAML frontmatter fields:
| Field | Description |
|-------|-------------|
| id | Lowercase slug (e.g., code-reviewer) |
| name | Display name (3–80 characters) |
| description | Short summary (10–240 characters) |
| version | SemVer format (e.g., 1.0.0) |
| category | One of 14 predefined categories |
Which tools support agent definitions?
Agent definitions work with any AI tool that supports Markdown-based configuration, including Claude Code (CLAUDE.md), Cursor (.cursorrules), Windsurf, GitHub Copilot, and 40+ tools that implement the Agent Skills specification.