Skill Creator

This skill provides guidance for creating effective skills for Antigravity IDE. Skills created with this tool are fully compatible with Claude Code Skills.

About Skills

Skills are modular, self-contained packages that extend the agent's abilities by providing specialized knowledge, workflows, and tools. They transform the agent from a general-purpose assistant into a specialized agent equipped with procedural knowledge for specific domains.

Anatomy of a Skill

skill-name/
├── SKILL.md (required)
│   ├── YAML frontmatter (required)
│   │   ├── name: (required)
│   │   └── description: (required)
│   └── Markdown instructions
└── Bundled Resources (optional)
    ├── scripts/      - Executable code
    ├── references/   - Documentation for context
    └── assets/       - Templates, images, files

Progressive Disclosure

Level	Content	When Loaded
1	Metadata	Always (~100 words)
2	SKILL.md body	When triggered (<5k words)
3	Bundled resources	As needed (unlimited)

When to Use This Skill

• Creating a new skill from scratch
• Updating an existing skill
• Packaging a skill for distribution
• Understanding skill best practices

Skill Creation Process

Step 1: Understand with Examples

Gather concrete examples of how the skill will be used:

• "What functionality should this skill support?"
• "Can you give examples of how it would be used?"
• "What would trigger this skill?"

Step 2: Plan Reusable Contents

For each example, analyze:

1. How to execute the task from scratch
2. What scripts, references, or assets would be helpful

Example analyses:

Skill	Query	Analysis	Resource
pdf-editor	"Rotate this PDF"	Same code each time	scripts/rotate_pdf.py
frontend-builder	"Build a todo app"	Same boilerplate each time	assets/hello-world/
big-query	"How many users today?"	Need schema each time	references/schema.md

Step 3: Initialize

Run the initialization script:

scripts/init_skill.py <skill-name> --path ~/.gemini/skills/

This creates:

• SKILL.md with proper frontmatter and TODOs
• Example scripts/, references/, assets/ directories
• Placeholder files to customize or delete

Step 4: Edit the Skill

Start with Resources

1. Create scripts for repeated code
2. Add references for documentation
3. Include assets for templates
4. Delete unused example directories

Complete SKILL.md

Answer these questions:

1. Purpose: What does this skill do? (few sentences)
2. When: When should it be used? (trigger conditions)
3. How: How should it be used? (reference all resources)

Writing Style

• Use imperative/infinitive form (verb-first instructions)
• Write objectively: "To accomplish X, do Y" not "You should do X"
• Keep SKILL.md lean; move details to references/

Step 5: Package (Optional)

For distributing skills:

scripts/package_skill.py <path/to/skill>

This validates and zips the skill.

Step 6: Iterate

After using the skill:

1. Notice struggles or inefficiencies
2. Identify needed updates
3. Implement changes
4. Test again

SKILL.md Best Practices

Frontmatter Quality

The name and description determine when the agent uses the skill:

• Be specific about what it does
• Use third person: "This skill should be used when..."
• Include trigger keywords

Structure Template

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

# Skill Name

Brief description of purpose.

## When to Use This Skill

- Bullet list of use cases
- Trigger conditions

## What This Skill Does

1. First thing it does
2. Second thing it does
3. Third thing it does

## How to Use

### Basic Usage
\`\`\`
Example prompt
\`\`\`

### Advanced Usage
\`\`\`
More complex example
\`\`\`

## Example

Full example with input and output.

## Tips for Success

Best practices and gotchas.

Resource Guidelines

Scripts (scripts/)

• Include when code is rewritten repeatedly
• Benefits: Token efficient, deterministic, executed without loading
• May need to be read for patching or environment adjustments

References (references/)

• Include for documentation the agent should reference
• Use cases: Schemas, API docs, policies, detailed guides
• Best practice: If large (>10k words), include grep patterns in SKILL.md

Assets (assets/)

• Include for files used in output
• Use cases: Templates, images, boilerplate code
• Benefits: Used without loading into context

Creating via Conversation

Instead of using scripts, you can ask:

Create a new skill called "X" that does Y. 
Include a script for Z and reference docs for W.

The agent will:

1. Create the directory structure
2. Write SKILL.md
3. Add requested resources
4. Update skills/README.md