# Agent Skill

> Part of the AI Garage Jargons glossary: https://aigarage.in/jargons (all terms: https://aigarage.in/jargons.md)

**Category:** Prompting
**Tags:** agents, skills, instructions, context

A folder of instructions, and optionally scripts and reference files, that an AI agent loads only when a task calls for it, with a SKILL.md file at its core that says what the skill does and how to do it.

**In plain terms:** It is a playbook the agent keeps on a shelf. It reads the title on the spine every time, and takes the whole playbook down only when the job needs it.

**Use cases:**
- Repeatable document and report tasks
- A team's house style and checklists
- Publishing workflows with fixed steps and exact checks

**Why it matters:** A prompt lives in one conversation. A skill packages the same guidance once, so the agent applies it every time, loads it only when needed, and can run bundled scripts for steps that must be exact. Whether a skill actually works is a separate question that testing answers.

**Why now:** Agent products now let people add their own skills, and Anthropic has published the Agent Skills format as an open standard. Availability and details vary by product, so check the current documentation before relying on a specific behavior.

**AI Garage example:** The AI Garage Jargons workflow is itself organized as a skill in this repository. A SKILL.md sets the steps, reference files hold the knowledge contract and script standards, and scripts run checks such as the script audit. This describes how the repository is organized, not a claim about production usage.

**Mental model:** A skill is reusable know-how that loads on demand. The agent always sees a short name and description, reads the full instructions only when the task matches, and opens extra files or runs bundled scripts only when needed. That keeps the context window light while the skill itself can hold a lot.

**Builder scenario: Stop re-explaining the same task to an agent**

- **Context:** A team asks an agent to publish a glossary entry every week, and each time pastes the same twelve instructions.
- **Failure:** The agent follows the instructions differently each time. Some steps are skipped, and nobody can tell which version of the instructions was used.
- **Intervention:** Package the steps as a skill: a short description that says when to use it, the full procedure in SKILL.md, reference files for the standards, and a script for the checks that must be exact.
- **Outcome:** The agent loads the procedure only for glossary work and runs the same checks each time, and the team improves one file instead of twelve pasted prompts.

**Common misconceptions:**
- **Claim:** A skill is just a longer prompt.
  **Correction:** A prompt lives in one conversation. A skill is a folder the agent discovers and loads on demand, and it can include reference files and scripts. Only its name and description are always in context.
- **Claim:** A skill makes the agent good at the task.
  **Correction:** A skill gives the agent instructions. Whether they work is a separate question, answered by testing the agent on real tasks, which is what evals do.

**Visual model (comparison):** The skill and the eval form a loop: teach with a skill, let the agent work, evaluate the results, then improve the skill from the failures that keep recurring. This is AI Garage's framing of the relationship.

**Visual description:** Two columns compare a skill and an eval. A skill teaches the agent how to approach a task and contains instructions, references, and scripts. An eval checks whether the agent can do the task and contains tasks, graders, and scores. Each improves the other.

**Related concepts:** [Prompt Engineering](https://aigarage.in/jargons/prompt-engineering), [Context Window](https://aigarage.in/jargons/context-window), [API](https://aigarage.in/jargons/api), [Evals](https://aigarage.in/jargons/evals), [AI Agent](https://aigarage.in/jargons/ai-agent)

**Last researched:** 2026-10-12

**Sources:**
- [Anthropic Engineering - Equipping agents for the real world with Agent Skills](https://www.anthropic.com/engineering/equipping-agents-for-the-real-world-with-agent-skills)
- [Claude Docs - Agent Skills overview](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/overview)
- [Anthropic - Agent Skills repository](https://github.com/anthropics/skills)

**URL:** https://aigarage.in/jargons/agent-skill