Skill Builder

A meta-skill for creating reusable, context-efficient agent skills.

Build skills that execute reliably under cognitive constraints—like checklists pilots use in emergencies, but for AI agents with limited context windows.

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The Problem

LLM agents are brilliant but forgetful. Every complex task gets reinvented from scratch, burning tokens on reasoning that could be reused. When context windows fill up, quality degrades.

Traditional routers are expensive: A router with 50 skills can consume 3000+ tokens just to pick the right one.

The Solution

Skill Builder generates structured SKILL.md files using an object-oriented format designed for:

• Fail-fast eligibility checks — exit in ~150 tokens if skill doesn't apply
• Lazy-loaded subclasses — only load enhancements when needed
• Explicit state management — prevent infinite loops with trial counters
• npm workspace routing — familiar package management, zero token search
• bun-first runtime — 10x faster execution with node fallback

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Architecture

Skill Structure (OOL)

MainExecution          ← Always loaded first (~500 tokens)
├── Constructor        ← Eligibility diagnosis (exit fast if wrong)
└── execute()          ← Minimum viable path

QualityOptimizer       ← Lazy-load when output quality is low
PerformanceOptimizer   ← Lazy-load when parallelization helps
ErrorHandler           ← Lazy-load when execution fails

Routing (bun + npm)

Instead of a custom router that burns tokens:

# Instant search with bun (recommended - 10x faster)
bun scripts/search_skills.js brainstorming
# Output: design-thinking-ideation

# Or with node (fallback)
node scripts/search_skills.js brainstorming

# Or if installed:
npm query "[keywords~=brainstorming]"
npm ls --depth=0

Why bun + npm?

• bun: 10x faster than node, instant startup, modern MCP standard
• npm: Built-in search via npm query, universal package.json
• Compatibility: Script works with both bun and node
• Already installed: Agents need bunx/npx for MCP servers anyway

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Usage

For Agent Users

Finding a skill:

# Search by keyword (instant, bun recommended)
bun scripts/search_skills.js brainstorming

# Or with node
node scripts/search_skills.js brainstorming

# Or install and query
npm install
npm query "[keywords~=brainstorming]"

# List all skills
npm ls --depth=0

Activating a skill:

// Search (bun for speed)
const result = terminal.execute("bun scripts/search_skills.js brainstorming");
const skill = result.trim();

// Activate
const skill_path = `skills/${skill}/SKILL.md`;
const skill_content = filesystem.read(skill_path);
execute(skill_content);

For Skill Authors

Create a new skill:

1. Use the skill-builder pipeline:

# Activate skill-builder
bun scripts/search_skills.js create-skill
# Returns: skill-builder

# Follow instructions in skills/skill-builder/SKILL.md

2. Place output in skills/your-skill-name/:

skills/your-skill-name/
├── package.json         # Dependencies + metadata
├── SKILL.md             # MainExecution class
└── resources/           # Optional subclasses
    ├── quality.md
    └── performance.md

3. Your skill is now discoverable

Skill template:

Use skills/skill-builder/resources/template.md as your starting point.

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Example: Design Thinking Ideation

package.json:

{
  "name": "@skills/design-thinking-ideation",
  "version": "1.0.0",
  "description": "Generate divergent solution concepts",
  "keywords": [
    "brainstorming",
    "divergent-thinking",
    "ideation"
  ],
  "agentskills": {
    "exit_when": [
      "Problem statement missing",
      "User wants convergent solution"
    ]
  },
  "dependencies": {}
}

SKILL.md: Same OOL format with constructor + execute()

Agent discovery:

$ bun scripts/search_skills.js ideation
design-thinking-ideation

$ npm ls --depth=0  # if installed
@skill-builder/[email protected]
├── @skills/[email protected]
└── @skills/[email protected]

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Repository Structure

skill-builder/
├── SKILL.md                  # Root router (~70 tokens)
├── package.json              # npm workspace definition
├── README.md
├── SETUP.md
│
├── scripts/
│   └── search_skills.js      # Instant search (bun/node compatible)
│
└── skills/                   # npm workspace packages
    ├── skill-builder/
    │   ├── package.json
    │   ├── SKILL.md
    │   └── resources/
    │
    ├── dependency-tree/
    │   ├── package.json
    │   └── SKILL.md
    │
    └── design-thinking-ideation/
        ├── package.json
        └── SKILL.md

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Performance

Search Speed:

• bun: ~5ms (50 skills)
• node: ~25ms (50 skills)
• python: ~25ms (50 skills)

Token Cost:

• Router load: 70 tokens (vs 3000+ for custom)
• Search: 0 tokens (external script)
• Activation: Skill-specific (~500-2000 tokens)

Result: 97% token reduction + 5x faster search with bun.

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Compatibility

Platform	Support
Gemini CLI	Native skill loading
Claude Code	Via MCP server
OpenAI Codex	Custom instructions
Agent Skills Protocol	Full compliance

Runtime Requirements:

• Recommended: bun >= 1.0.0 (for speed)
• Fallback: node >= 16.0.0 (for compatibility)

MCP Tools Supported:

• github-mcp — repository operations
• filesystem — local file access
• terminal — command execution

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Contributing

Add a New Skill

1. Fork this repo
2. Create skills/your-skill-name/
3. Add package.json + SKILL.md
4. Test with bun and node
5. Submit PR

Report Issues

Found a bug? Open an issue with:

• Skill name
• Runtime (bun/node version)
• Agent platform (Gemini/Claude/GPT)
• Expected vs actual behavior
• Steps to reproduce

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References

• Agent Skills Specification
• Gemini CLI Skills Documentation
• Model Context Protocol
• npm Workspaces
• bun Documentation

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License

MIT — use it, fork it, make agents that actually remember how to do things.

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Read less, do more. Built with bun + npm workspaces.