Skill

Overview
What it is	A reusable instruction package added to an agent's system prompt
CLI	agt skill
Agent tools	resource_* with kind: "skill"
Web console	Resources → Skill; Skills in the agent form
File	skills/<category>/<package>/SKILL.md
Crate	agt-skill

What it does

A skill packages instructions for one kind of work, such as "how we review code" or "how to run the release checklist", so you can attach it to any agent instead of copying it into every prompt. When a run starts, the full text of every attached skill is added to the agent's instructions. Codex agents receive skills too.

Skills use the SKILL.md format: Markdown with a YAML front matter. Packages can be scoped, such as @team/review.

How to use it

Web console: Resources → New resource → Skill creates a skeleton with a name and description. Write the full instructions with the CLI.

CLI:

agt skill create code-review --description 'Review source code for correctness and style'
agt skill update code-review --file ./code-review/SKILL.md
agt skill read code-review
agt agent update reviewer --add-skill code-review

Agent tools:

{"kind":"skill","reference":"code-review","create":true,"data":{"description":"Review source code"}}
{"kind":"skill","reference":"code-review","create":false,"data":{"text":"---\nname: code-review\n..."}}

Common parameters

Parameter	Meaning
--description	One-line summary, shown in lists
--file	A SKILL.md file, or a directory that contains one

All parameters

agt skill create <package>

Option	Required	Meaning
--description <text>	yes	Summary, at most 1024 characters
--category <c>	no	Category (default default)

Creates a SKILL.md with the name, the description and a placeholder body.

agt skill update <package>

Option	Required	Meaning
--file <path>	yes	A SKILL.md file or a directory containing it. Replaces the whole file.
--category <c>	no	Category

Other commands

Command	Meaning
read <ref>	Print SKILL.md
list, info, delete, category	See Resources

File: SKILL.md

---
name: code-review
description: Review source code for correctness and style
license: MIT
---
# Code review

1. Read the whole change before commenting.
2. ...

Front matter field	Required	Meaning
name	yes	Package name; must match the directory
description	yes	Summary, at most 1024 characters
license	no	License of the instructions
compatibility	no	Compatibility notes, at most 500 characters
metadata	no	String map. For scoped packages, agt.package holds the full name, such as @team/review; its last part must equal name.
allowed-tools	no	Not supported yet: an agent with such a skill fails to run

Tool fields (resource_write, kind: "skill")

Field	When	Meaning
description	create	Summary; creates the skeleton
text	update	The complete new SKILL.md, front matter included

Related modules

• Agent: attaching skills
• Prompt: the base role description