asets-gobizit/z-antigravity-skill-creator

Antigravity Skill Creator

Generate high-quality, predictable, and efficient .agent/skills/ directories for the Antigravity agent environment.

When to use this skill

• User asks to create a skill for the Antigravity agent
• User mentions .agent/skills/ directory structure
• User wants a SKILL.md generated following Antigravity conventions
• User says "build me a skill for [task]" in the context of Antigravity

Core Structural Requirements

Every skill must follow this folder hierarchy:

<skill-name>/
├── SKILL.md              # Required: Main logic and instructions
├── brand_context.md      # Recommended: Brand voice, tone, messaging guidelines
├── scripts/              # Optional: Helper scripts
├── examples/             # Recommended: Reference outputs showing target quality
└── resources/            # Optional: Templates or assets

Brand Context (Recommended)

Every skill that generates user-facing content (websites, copy, emails, social posts, documents) should include a brand_context.md file. This file tells the agent HOW to sound, not just WHAT to build.

A good brand_context.md covers:

• Company name, slogan, and key messaging
• Target audience profile
• Tone & voice guidelines (e.g., "professional but human")
• Pain points the brand addresses
• Differentiators / unique selling points
• Language do's and don'ts (words to use vs. avoid)
• CTA style and examples
• Visual/design notes (colors, typography, image style)

When creating a skill, ask the user: "Does this skill generate content for a specific brand? If so, I'll create a brand_context.md to keep outputs on-brand."

Examples Folder (Recommended)

The examples/ folder should contain reference outputs that show the target quality and style. These act as "gold standard" samples the agent can match against. Include:

• Real or representative output from the skill
• Annotated examples showing good vs. bad output
• Style references (e.g., extracted sections from an existing site or document)

YAML Frontmatter Standards

The SKILL.md must start with YAML frontmatter:

• name: Gerund form (e.g., testing-code, managing-databases). Max 64 chars. Lowercase, numbers, and hyphens only. Never include "claude" or "anthropic" in the name.
• description: Written in third person. Must include specific triggers/keywords. Max 1024 chars.

Example:

---
name: testing-code
description: "Extracts text from PDFs. Use when the user mentions document processing or PDF files."
---

Writing Principles

These principles ensure Claude (or any agent consuming the skill) can follow the instructions efficiently:

• Conciseness: The agent is smart. Don't explain basics. Focus only on the unique logic of the skill.
• Progressive Disclosure: Keep SKILL.md under 500 lines. For extended detail, link to secondary files (e.g., [See ADVANCED.md](ADVANCED.md)) — only one level deep.
• Forward Slashes: Always use / for paths, never \.
• Degrees of Freedom:
  • Bullet points for high-freedom tasks (heuristics, judgment calls)
  • Code blocks for medium-freedom (templates, formats)
  • Specific bash commands for low-freedom (fragile or exact operations)

Workflow & Feedback Loops

For complex tasks, the generated skill should include:

1. Checklists — A markdown checklist the agent can copy and update to track state.
2. Validation Loops — A "Plan-Validate-Execute" pattern. Run a check script BEFORE applying changes.
3. Error Handling — Scripts should be "black boxes." Tell the agent to run --help if unsure.

Output Template

When asked to create a skill, produce output in this format:

### [Folder Name]
**Path:** `.agent/skills/[skill-name]/`

### SKILL.md
---
name: [gerund-name]
description: [3rd-person description with triggers]
---

# [Skill Title]

## When to use this skill
- [Trigger 1]
- [Trigger 2]

## Workflow
[Checklist or step-by-step guide]

## Instructions
[Specific logic, code snippets, or rules]

## Resources
- [Links to scripts/ or resources/]

Then provide supporting files (scripts, examples) if applicable.

If the skill generates user-facing content, also produce:

• brand_context.md — Interview the user for brand details (tone, audience, language rules, CTA style) and capture them in this file.
• examples/[style-reference].md — At least one reference output showing target quality, structure, and tone.

Quality Checklist

Before delivering a skill, verify:

• [ ] SKILL.md has valid YAML frontmatter
• [ ] Name is gerund-form, lowercase+hyphens, under 64 chars
• [ ] Description is third-person with trigger keywords, under 1024 chars
• [ ] Body is under 500 lines
• [ ] Paths use forward slashes only
• [ ] Instructions match the appropriate degree-of-freedom format
• [ ] Complex workflows include validation loops
• [ ] No "claude" or "anthropic" in the skill name
• [ ] Content-generating skills include brand_context.md (or user confirmed not needed)
• [ ] At least one example output in examples/ for content-generating skills