Skill Creator

Skill Creator

This skill provides a practical, spec-aligned workflow for creating and maintaining Agent Skills.

Specification (Required Format)

Directory structure

A skill is a directory containing at minimum a SKILL.md file:

skill-name/
└── SKILL.md

Optional directories: scripts/, references/, and assets/.

SKILL.md frontmatter (required)

---
name: skill-name
description: A description of what this skill does and when to use it.
---

Optional fields:

---
name: pdf-processing
description: Extract text and tables from PDF files, fill forms, merge documents.
license: Apache-2.0
compatibility: Requires git, python3, and internet access
metadata:
  author: example-org
  version: "1.0"
allowed-tools: Bash(git:*) Bash(jq:*) Read
---

name field rules

• Must be 1-64 characters
• Only lowercase letters, digits, and hyphens (a-z, 0-9, -)
• Must not start or end with -
• Must not contain --
• Must match the skill directory name

Valid:

name: pdf-processing
name: data-analysis
name: code-review

Invalid:

name: PDF-Processing
name: -pdf
name: pdf--processing

description field rules

• Must be 1-1024 characters
• Should include both what the skill does and when to use it
• Include keywords that help agents route relevant tasks

Good:

description: Extracts text and tables from PDF files, fills PDF forms, and merges multiple PDFs. Use when working with PDFs, forms, or document extraction.

Poor:

description: Helps with PDFs.

Core Principles

Be concise

The context window is shared across system prompt, conversation, skill metadata, and task input. Assume the agent is capable and only include non-obvious, high-value information.

Set appropriate degrees of freedom

• High freedom: heuristics and decision guidance
• Medium freedom: pseudocode or scripts with parameters
• Low freedom: deterministic scripts and strict sequences

Use tighter constraints when tasks are fragile, error-prone, or require high consistency.

Anatomy of a Skill

A skill includes a required SKILL.md plus optional bundled resources:

skill-name/
├── SKILL.md
├── scripts/        # Executable helpers
├── references/     # Docs loaded on demand
└── assets/         # Templates, images, data

scripts/

Use for repeatable code or fragile operations that benefit from deterministic execution.

references/

Use for large or detailed docs that should load only on demand (schemas, API docs, policies).

assets/

Use for static resources that get copied or reused in outputs (templates, images, fonts, boilerplate).

What not to include

Avoid extra docs that do not directly help an agent complete tasks (README.md, INSTALLATION_GUIDE.md, CHANGELOG.md, etc.).

Progressive Disclosure

1. Metadata (name + description) always loads
2. SKILL.md body loads when the skill triggers
3. Resources load only when needed

Keep SKILL.md under 500 lines. Move deep references to references/ and link them from SKILL.md.

Patterns

Pattern 1: High-level guide with references

# PDF Processing

## Quick start

Extract text with pdfplumber:
[code example]

## Advanced features

- Form filling: See references/FORMS.md
- API reference: See references/REFERENCE.md
- Examples: See references/EXAMPLES.md

Pattern 2: Domain-specific organization

bigquery-skill/
├── SKILL.md
└── references/
    ├── finance.md
    ├── sales.md
    ├── product.md
    └── marketing.md

Pattern 3: Conditional details

# DOCX Processing

## Creating documents

Use docx-js for new documents. See references/DOCX-JS.md.

## Editing documents

For simple edits, modify the XML directly.

For tracked changes: references/REDLINING.md
For OOXML details: references/OOXML.md

Guidelines:

• Keep references one level deep from SKILL.md
• Add a table of contents for reference files over ~100 lines

Skill Creation Process

1. Understand the skill with concrete examples
2. Plan reusable contents (scripts, references, assets)
3. Initialize a new skill
4. Edit SKILL.md and bundled resources
5. Validate and package
6. Iterate based on real usage

Step 1: Understand with examples

Gather representative user requests and clarify edge cases. Avoid too many questions per message; start with the highest-impact unknowns.

Step 2: Plan reusable contents

For each example, identify what should be scripted, documented, or templated. Convert repeated logic into scripts or reusable assets.

Step 3: Initialize the skill

Use the initializer script (from this skill directory):

./scripts/init_skill.py <skill-name> --path <output-directory>

The script creates a new skill folder with a template SKILL.md plus example scripts/, references/, and assets/ directories. Remove any unused examples.

Step 4: Edit the skill

Write concise, action-oriented instructions. Use imperative language. Ensure the frontmatter matches the spec and the directory name.

Consult references if you need patterns:

• references/workflows.md
• references/output-patterns.md

Step 5: Validate

Preferred validator (spec reference library):

skills-ref validate ./my-skill

Quick local validator (bundled with this skill):

./scripts/quick_validate.py ./my-skill

Step 6: Package

./scripts/package_skill.py <path/to/skill-folder> [output-directory]

The packager validates first, then creates <skill-name>.skill (zip format).

Step 7: Iterate

Run the skill on real tasks, note failures or friction, and update SKILL.md or resources accordingly.

File references

Use relative paths from the skill root:

See references/REFERENCE.md for details.
Run scripts/extract.py for extraction.

Avoid deeply nested reference chains.