---

name: skill-creator description: Use when asked to create or update skills or extend agent capabilities in this configuration. allowed-tools: ["write_file", "read_file"] metadata: short-description: Create new Codex skills systematically

Skill Creator

Guide for creating new Codex skills with the same rigor as existing ones.

Context Efficiency (Anthropic Principle)

The context window is a public good. Only include what the model does not already know. Prefer concise guidance and move heavy references into separate files.

Degree of Freedom Matching

Match instruction specificity to task fragility:

• Low freedom for fragile, error-prone workflows
• High freedom for exploratory work

Progressive Disclosure

Use a three-layer structure:

1. Frontmatter for triggers only
2. SKILL.md body for workflow guidance
3. References/scripts/assets for heavy details

TDD for Skills (Discipline)

Before creating or editing a skill:

• Define pressure scenarios that the skill must handle
• Validate behavior before/after changes
• Iterate to close loopholes

Core Principle: Explicit References

Never summarize guidance documents. Always instruct to read the full documents, allowing all guidance to apply.

Bad (summarizing):

CopyPer quality.md:
- Correctness first
- Then safety

Good (explicit read):

Copy**Read these references:**
- `~/.config/agent/domain/coding/quality.md` - Complete quality priorities

File Locations

All files in chezmoi source: ~/.local/share/chezmoi/home/

Skill Files (Parity Required):

• Claude Code: dot_claude/skills/<name>/SKILL.md
• Codex: dot_codex/skills/<name>/SKILL.md
• Keep both in sync (strict parity)

Apply with chezmoi:

Copychezmoi apply ~/.codex

Creating a Codex Skill

Template:

Copy---
name: skill-name
description: Use when <trigger conditions only; no workflow summary>
allowed-tools: ["shell", "apply_patch", "read_file", "write_file"]
metadata:
  short-description: Brief one-liner
---

# Skill Title

**Read these references:**
- `references/file1.md` - Purpose/summary
- `~/.config/agent/path/to/file2.md` - Purpose/summary

## Instructions

<Skill-specific guidance>

Apply all guidance from references listed above.

## Arguments

Target: ${ARGUMENTS}

Key points:

• description field triggers auto-activation - be specific about triggers
• allowed-tools is JSON array format: ["shell", "read_file"]
• metadata.short-description for UI display
• Use ${ARGUMENTS} for argument substitution (NOT $ARGUMENTS)
• No @ includes - use explicit "Read these references" instead

Reference Formats:

• Local (via symlink): references/file.md
• Direct path: ~/.config/agent/path/to/file.md
• AGENT.md is auto-loaded for all profiles

Creating References Symlink

For skills needing domain-specific guidance:

Copy# In deployed directory (NOT chezmoi source!)
cd ~/.codex/skills/skill-name
ln -s ~/.config/agent/domain/path references

# If also using Claude Code, mirror the same symlink:
cd ~/.claude/skills/skill-name
ln -s ~/.config/agent/domain/path references

Example: Go skills symlink to ~/.config/agent/domain/coding/go

Workflow for Creating New Skills

1. Identify Purpose

• What problem does this solve?
• When should it activate?
• What tools does it need?
• Is it command-style (explicit invocation) or auto-activation?

2. Identify Relevant Guidance

Which modules from ~/.config/agent/ apply?

• core/ - Universal behaviors (methodology, task-management, etc.)
• domain/ - Domain-specific (coding, testing, review, architecture)
• workflows/ - Task workflows (feature implementation, etc.)

3. Design Skill Structure

• Frontmatter: name, description (with triggers), allowed-tools, metadata
• References section: List all guidance files to read
• Instructions: Skill-specific logic
• Arguments section: How to use ${ARGUMENTS}

4. Write SKILL.md File

In chezmoi source: ~/.local/share/chezmoi/home/dot_codex/skills/<name>/SKILL.md

• Use explicit read instructions (not summaries)
• List ALL relevant guidance files
• Keep instructions focused and minimal
• Reference AGENT.md where applicable

5. Apply with Chezmoi

Copychezmoi apply ~/.codex

6. Create References Symlink (if needed)

In deployed directory: ~/.codex/skills/<name>/

Copyln -s ~/.config/agent/domain/path references

7. Test

• Invoke skill: $skill-name <arguments>
• Verify skill activates correctly
• Confirm references are readable
• Validate guidance is being applied

Existing Guidance Modules

All paths relative to ~/.config/agent/:

Core:

• core/behavior.md - Critical thinking, evidence-based reasoning
• core/communication.md - Tone, style, conciseness
• core/methodology.md - 5-phase problem-solving
• core/efficiency.md - Parallelization, throughput
• core/task-management.md - TODO discipline
• core/principles.md - Engineering principles

Architecture:

• domain/architecture/decomposition.md - Problem breakdown
• domain/architecture/parallelization.md - Concurrent execution

Coding (General):

• domain/coding/workflow.md - Universal coding workflow
• domain/coding/quality.md - Quality priorities
• domain/coding/safety.md - Runtime + security safety

Coding (Go):

• domain/coding/go/style.md - Go code style
• domain/coding/go/idioms.md - Go conventions
• domain/coding/go/concurrency.md - Go thread safety
• domain/coding/go/testing.md - Go test practices
• domain/coding/go/tooling.md - Go commands
• domain/coding/go/organization.md - Go code structure
• domain/coding/go/performance.md - Go optimization

Testing:

• domain/testing/unit.md - Unit test strategies
• domain/testing/coverage.md - Coverage requirements

Review:

• domain/review/process.md - Review workflow
• domain/review/priorities.md - Review focus areas

Workflows:

• workflows/feature.md - Feature implementation

Anti-Patterns to Avoid

❌ Summarizing guidance:

CopyFrom quality.md, the priorities are: correctness, safety...

❌ Selective quoting:

CopyKey rules: Rule A, Rule B

❌ Using @ includes (doesn't work in Codex):

CopyApply all guidance from:
- @~/.config/agent/file.md

✅ Explicit read instructions:

Copy**Read these references:**
- `references/file.md` - Complete guidance on topic
- `~/.config/agent/path/to/file.md` - Full details

Examples

See existing Codex skills:

• ~/.codex/skills/go-development/SKILL.md - With references symlink
• ~/.codex/skills/go-test/SKILL.md - Command-style skill
• ~/.codex/skills/problem-solving/SKILL.md - With multiple references
• ~/.codex/skills/feature/SKILL.md - Workflow orchestration