SKILL: Create Skill
Last Updated: February 5, 2026
Table of Contents
1. Overview
Guides creation of SKILL files per the agentskills.io specification. A SKILL file defines a repeatable task for AI agents: YAML frontmatter (metadata), body content (instructions), and optional directories (scripts, references, assets).
Use when: Task is repeatable, multiple users benefit, requires domain knowledge, output should be standardized.
Do NOT use when: One-time task, existing skills cover it, task too simple, no structured output needed.
2. Required Components
2.1 YAML Frontmatter
🚨 CRITICAL: Must comply with agentskills.io specification.
| Field | Required | Constraints |
|---|---|---|
name | Yes | 1-64 chars, lowercase a-z, numbers, hyphens. No --, no leading/trailing - |
description | Yes | 1-1024 chars. What it does AND when to use it. |
license | No | License name or bundled file reference |
compatibility | No | Environment requirements (max 500 chars) |
metadata | No | Custom key-value fields (author, version, keywords, etc.) |
Name Rules: Must start with verb (validate, process, analyze, create, review), match parent directory name.
Example:
---
name: validate-order
description: Validates restaurant order data against menu and inventory constraints. Use when processing customer orders.
metadata:
author: example-org
version: 1.0
display-name: Validate Order
keywords: [order, validate, menu]
example-prompt:
- Validate the order data in OrderController.cs
---
2.2 Document Structure
| Section | Required | Purpose |
|---|---|---|
| YAML Frontmatter | Yes | Discovery metadata |
| H1 Title | Yes | # SKILL: {topic_name} |
| Last Updated | Yes | **Last Updated:** Month DD, YYYY |
| TOC | Yes | All H2/H3 sections with anchors |
| Overview | Yes | One-liner intro + what/when |
| Execution Workflow | Yes | Step-by-step process |
| Self-Assessment | Yes | Verification checklist |
| Output Template | No | Expected result format |
Keep under 500 lines per RULE_Document.md. Move detailed references to references/ directory.
2.3 Optional Directories
.ai-toolbox/skills/{skill_name}/
├── SKILL.md # Required
├── scripts/ # Executable code (Python, Bash, JS)
├── references/ # Additional documentation
└── assets/ # Templates, images, data files
3. Execution Workflow
Step 1: Gather Requirements
- •Identify repeatable task to automate
- •List inputs, outputs, decision points
- •Review existing SKILL files for patterns
Step 2: Define Metadata
- •Choose
name(lowercase, hyphens, verb-first, max 64 chars) - •Write
description(max 1024 chars, what AND when) - •Add optional fields under
metadata
Step 3: Write Content
- •Overview section (one-liner intro + purpose)
- •Execution Workflow (4-6 steps)
- •Self-Assessment Protocol with
🚨 CRITICALmarker
Step 4: Optimize and Validate
- •Remove redundant words, use tables for structured data
- •Verify frontmatter complies with spec
- •Confirm under 500 lines
Step 5: Finalize
- •Run
format-markdownskill - •Verify all changes applied correctly
Output (File): .ai-toolbox/skills/{skill_name}/SKILL.md (template: assets/TEMPLATE_Skill.md)
4. Best Practices
Workflow Format:
| Element | Format | Example |
|---|---|---|
| Step header | **Step N: [Verb + Object]** | **Step 1: Load Rules** |
| Step count | 4-6 steps (optimal) | Not 3, not 7+ |
| Sub-steps | Numbered list (1, 2, 3...) | 1. Read file |
| Output | `**Output (File | Console):**` |
Progressive Disclosure: Metadata (~100 tokens) loaded at startup, full body (<5000 tokens) when activated, resources loaded on demand.
Common Mistakes:
| Mistake | Fix |
|---|---|
| Invalid name format | Lowercase, hyphens only, no -- |
| Description too vague | Include what AND when to use |
| SKILL.md too long | Move details to references/ |
| Non-spec frontmatter | Use metadata for custom fields |
Token Optimization: Use tables over prose, prefer bullets over paragraphs, replace "it/this/that" with specific nouns.
5. Self-Assessment Protocol
🚨 CRITICAL: Before presenting results, verify:
Frontmatter:
- •
nameis 1-64 chars, lowercase, hyphens, starts with verb - •
namehas no--, doesn't start/end with hyphen - •
descriptionis 1-1024 chars, explains what AND when - • Custom fields placed under
metadata
Structure:
- • H1 follows
# SKILL: {topic_name}format - • Last Updated date present
- • TOC includes all H2/H3 sections
- • Overview, Execution Workflow, Self-Assessment present
Quality:
- • SKILL.md under 500 lines
- • Steps are specific and actionable
- • Run
format-markdownskill validation - • No redundant words or filler phrases
6. Variable Reference
| Variable | Description | Example |
|---|---|---|
{skill_name} | Verb-first name (max 64 chars) | validate-order |
{skill_description} | What AND when (max 1024 chars) | Validates order data... |
{author} | Skill author | example-org |
{version} | Semantic version | 1.0 |
{display_name} | Title case name | Validate Order |
{keyword_n} | Keywords (n = 1, 2, 3) | order, validate |
{example_prompt_n} | Example invocations | Validate the order... |
{topic_name} | Title case topic for H1 | Validate Order |