| name | ring:writing-skills |
| description | TDD for process documentation - write test cases (pressure scenarios), watch
baseline fail, write skill, iterate until bulletproof against rationalization.
|
| license | MIT |
| compatibility | opencode |
| metadata | {"trigger":"Creating a new skill, editing an existing skill, skill needs to resist rationalization","skip_when":"Writing pure reference skill (API docs), skill has no compliance costs"} |
Writing Skills
Overview
Writing skills IS Test-Driven Development applied to process documentation.
Personal skills live in agent-specific directories (e.g., ~/.claude/skills for Claude Code, ~/.codex/skills for Codex, or custom agent directories)
You write test cases (pressure scenarios with subagents), watch them fail (baseline behavior), write the skill (documentation), watch tests pass (agents comply), and refactor (close loopholes).
Core principle: If you didn't watch an agent fail without the skill, you don't know if the skill teaches the right thing.
REQUIRED BACKGROUND: You MUST understand ring:test-driven-development before using this skill. That skill defines the fundamental RED-GREEN-REFACTOR cycle. This skill adapts TDD to documentation.
Official guidance: For Anthropic's official skill authoring best practices, see anthropic-best-practices.md. This document provides additional patterns and guidelines that complement the TDD-focused approach in this skill.
What is a Skill?
A skill is a reference guide for proven techniques, patterns, or tools. Skills help future agent instances find and apply effective approaches.
Skills are: Reusable techniques, patterns, tools, reference guides
Skills are NOT: Narratives about how you solved a problem once
TDD Mapping for Skills
| TDD Concept | Skill Creation |
|---|
| Test case | Pressure scenario with subagent |
| Production code | Skill document (SKILL.md) |
| Test fails (RED) | Agent violates rule without skill (baseline) |
| Test passes (GREEN) | Agent complies with skill present |
| Refactor | Close loopholes while maintaining compliance |
| Write test first | Run baseline scenario BEFORE writing skill |
| Watch it fail | Document exact rationalizations agent uses |
| Minimal code | Write skill addressing those specific violations |
| Watch it pass | Verify agent now complies |
| Refactor cycle | Find new rationalizations → plug → re-verify |
The entire skill creation process follows RED-GREEN-REFACTOR.
When to Create a Skill
Create when:
- Technique wasn't intuitively obvious to you
- You'd reference this again across projects
- Pattern applies broadly (not project-specific)
- Others would benefit
Don't create for:
- One-off solutions
- Standard practices well-documented elsewhere
- Project-specific conventions (put in CLAUDE.md)
Skill Types
Technique
Concrete method with steps to follow (condition-based-waiting, root-cause-tracing)
Pattern
Way of thinking about problems (flatten-with-flags, test-invariants)
Reference
API docs, syntax guides, tool documentation (office docs)
Directory Structure
skills/skill-name/SKILL.md (required) + optional supporting files. Flat namespace.
Separate files for: Heavy reference (100+ lines), reusable tools. Keep inline: Principles, code patterns (<50 lines).
SKILL.md Structure
Frontmatter (YAML):
- Only two fields supported:
name and description
- Max 1024 characters total
name: Use letters, numbers, and hyphens only (no parentheses, special chars)description: Third-person, includes BOTH what it does AND when to use it
- Start with "Use when..." to focus on triggering conditions
- Include specific symptoms, situations, and contexts
- Keep under 500 characters if possible
---
name: ring:Skill-Name-With-Hyphens
description: Use when [triggers/symptoms] - [what it does, third person]
---
# Skill Name
## Overview (1-2 sentences), ## When to Use (symptoms, NOT to use)
## Core Pattern (before/after code), ## Quick Reference (table for scanning)
## Implementation (inline or link), ## Common Mistakes, ## Real-World Impact (optional)
Agent Search Optimization (ASO)
Critical for discovery: Future agents need to FIND your skill
1. Rich Description Field
Purpose: Agents read description to decide which skills to load for a given task. Make it answer: "Should I read this skill right now?"
Format: Start with "Use when..." to focus on triggering conditions, then explain what it does
Content:
- Use concrete triggers, symptoms, and situations that signal this skill applies
- Describe the problem (race conditions, inconsistent behavior) not language-specific symptoms (setTimeout, sleep)
- Keep triggers technology-agnostic unless the skill itself is technology-specific
- If skill is technology-specific, make that explicit in the trigger
- Write in third person (injected into system prompt)
| Quality | Example |
|---|
| BAD | For async testing (vague), I can help... (first person), setTimeout/sleep (tech-specific but skill isn't) |
| GOOD | Use when tests have race conditions... - replaces timeouts with condition polling (problem + solution) |
2. Keyword Coverage
Use words agents would search for:
- Error messages: "Hook timed out", "ENOTEMPTY", "race condition"
- Symptoms: "flaky", "hanging", "zombie", "pollution"
- Synonyms: "timeout/hang/freeze", "cleanup/teardown/afterEach"
- Tools: Actual commands, library names, file types
3. Descriptive Naming
Use active voice, verb-first:
- ✅
creating-skills not skill-creation
- ✅
testing-skills-with-subagents not subagent-skill-testing
4. Token Efficiency (Critical)
Problem: getting-started and frequently-referenced skills load into EVERY conversation. Every token counts.
Target word counts by skill type:
- Bootstrap/Getting-started: <150 words each (loads in every session)
- Simple technique skills: <500 words (procedures, patterns, single concept)
- Discipline-enforcing skills: <2,000 words (TDD, verification, systematic debugging - need rationalization tables)
- Process/workflow skills: <4,000 words (multi-phase workflows with comprehensive templates)
Rationale: Complex skills need extensive rationalization prevention and complete templates. Don't artificially compress at the cost of effectiveness.
Techniques: Reference --help instead of documenting flags. Cross-reference other skills instead of repeating. Compress examples (42 words → 20 words). Don't repeat cross-referenced content.
Verify: wc -w skills/path/SKILL.md (check against word counts above)
Name by what you DO or core insight:
- ✅
ring:condition-based-waiting > async-test-helpers
- ✅
using-skills not skill-usage
- ✅
flatten-with-flags > data-structure-refactoring
- ✅
ring:root-cause-tracing > debugging-techniques
Gerunds (-ing) work well for processes:
creating-skills, testing-skills, debugging-with-logs- Active, describes the action you're taking
4. Cross-Referencing Other Skills
When writing documentation that references other skills:
Use skill name only, with explicit requirement markers:
- ✅ Good:
**REQUIRED SUB-SKILL:** Use ring:test-driven-development
- ✅ Good:
**REQUIRED BACKGROUND:** You MUST understand systematic-debugging
- ❌ Bad:
See skills/testing/test-driven-development (unclear if required)
- ❌ Bad:
@skills/testing/test-driven-development/SKILL.md (force-loads, burns context)
Why no @ links: @ syntax force-loads files immediately, consuming 200k+ context before you need them.
Flowchart Usage
Only for: Non-obvious decisions, process loops, "A vs B" choices. Never for: Reference (→tables), code (→blocks), linear steps (→lists). See graphviz-conventions.dot for conventions.
Code Examples
One excellent example in most relevant language. Complete, well-commented WHY, real scenario, ready to adapt. Don't: multi-language, fill-in-blank templates, contrived examples.
File Organization
| Type | Structure | When |
|---|
| Self-Contained | skill/SKILL.md only | All content fits inline |
| With Tool | SKILL.md + example.ts | Reusable code, not narrative |
| Heavy Reference | SKILL.md + *.md refs + scripts/ | Reference >100 lines |
The Iron Law (Same as TDD)
NO SKILL WITHOUT A FAILING TEST FIRST
This applies to NEW skills AND EDITS to existing skills.
Write skill before testing? Delete it. Start over.
Edit skill without testing? Same violation.
No exceptions:
- Not for "simple additions"
- Not for "just adding a section"
- Not for "documentation updates"
- Don't keep untested changes as "reference"
- Don't "adapt" while running tests
- Delete means delete
REQUIRED BACKGROUND: The ring:test-driven-development skill explains why this matters. Same principles apply to documentation.
Testing All Skill Types
| Skill Type | Examples | Test With | Success Criteria |
|---|
| Discipline (rules) | TDD, verification | Pressure scenarios (time + sunk cost + exhaustion), academic questions | Agent follows rule under maximum pressure |
| Technique (how-to) | condition-based-waiting, root-cause-tracing | Application + variation + gap testing | Agent applies technique to new scenario |
| Pattern (mental model) | reducing-complexity | Recognition + application + counter-examples | Agent identifies when/how to apply |
| Reference (docs/APIs) | API docs, command refs | Retrieval + application + gap testing | Agent finds and applies info correctly |
Common Rationalizations for Skipping Testing
| Excuse | Reality |
|---|
| "Skill is obviously clear" | Clear to you ≠ clear to other agents. Test it. |
| "It's just a reference" | References can have gaps, unclear sections. Test retrieval. |
| "Testing is overkill" | Untested skills have issues. Always. 15 min testing saves hours. |
| "I'll test if problems emerge" | Problems = agents can't use skill. Test BEFORE deploying. |
| "Too tedious to test" | Testing is less tedious than debugging bad skill in production. |
| "I'm confident it's good" | Overconfidence guarantees issues. Test anyway. |
| "Academic review is enough" | Reading ≠ using. Test application scenarios. |
| "No time to test" | Deploying untested skill wastes more time fixing it later. |
All of these mean: Test before deploying. No exceptions.
Bulletproofing Skills Against Rationalization
Skills that enforce discipline (like TDD) need to resist rationalization. Agents are smart and will find loopholes when under pressure.
Psychology note: Understanding WHY persuasion techniques work helps you apply them systematically. See persuasion-principles.md for research foundation (Cialdini, 2021; Meincke et al., 2025) on authority, commitment, scarcity, social proof, and unity principles.
Close Every Loophole Explicitly
Don't just state rule - forbid specific workarounds:
- BAD:
Write code before test? Delete it.
- GOOD: Add
Delete it. Start over. + explicit No exceptions: list (don't keep as reference, don't adapt, don't look, delete means delete)
Address "Spirit vs Letter" Arguments
Add foundational principle early:
**Violating the letter of the rules is violating the spirit of the rules.**
This cuts off entire class of "I'm following the spirit" rationalizations.
Build Rationalization Table
Capture rationalizations from baseline testing (see Testing section below). Every excuse agents make goes in the table:
| Excuse | Reality |
|--------|---------|
| "Too simple to test" | Simple code breaks. Test takes 30 seconds. |
| "I'll test after" | Tests passing immediately prove nothing. |
| "Tests after achieve same goals" | Tests-after = "what does this do?" Tests-first = "what should this do?" |
Create Red Flags List
Make it easy for agents to self-check when rationalizing:
## Red Flags - STOP and Start Over
- Code before test
- "I already manually tested it"
- "Tests after achieve the same purpose"
- "It's about spirit not ritual"
- "This is different because..."
**All of these mean: Delete code. Start over with TDD.**
Update CSO for Violation Symptoms
Add to description: symptoms of when you're ABOUT to violate the rule:
description: use when implementing any feature or bugfix, before writing implementation code
RED-GREEN-REFACTOR for Skills
| Phase | Action |
|---|
| RED | Run pressure scenario WITHOUT skill → document choices/rationalizations verbatim |
| GREEN | Write skill addressing specific failures → verify agent complies |
| REFACTOR | Find new rationalizations → add counters → re-test until bulletproof |
REQUIRED SUB-SKILL: Use testing-skills-with-subagents for pressure scenarios, pressure types, hole-plugging, meta-testing.
Anti-Patterns
| Pattern | Example | Why Bad |
|---|
| Narrative | "In session 2025-10-03, we found..." | Too specific, not reusable |
| Multi-language | example-js.js, example-py.py | Mediocre quality, maintenance burden |
| Code in flowcharts | step1 [label="import fs"] | Can't copy-paste, hard to read |
| Generic labels | helper1, step3, pattern4 | Labels need semantic meaning |
STOP: Before Moving to Next Skill
After writing ANY skill, you MUST STOP and complete the deployment process.
Do NOT:
- Create multiple skills in batch without testing each
- Move to next skill before current one is verified
- Skip testing because "batching is more efficient"
The deployment checklist below is MANDATORY for EACH skill.
Deploying untested skills = deploying untested code. It's a violation of quality standards.
Skill Creation Checklist (TDD Adapted)
Use TodoWrite for each phase.
| Phase | Requirements |
|---|
| RED | 3+ pressure scenarios, run WITHOUT skill, document rationalizations verbatim |
| GREEN | Name (letters/numbers/hyphens), YAML frontmatter (<1024 chars), description starts "Use when...", third person, keywords, address baseline failures, one excellent example, verify compliance |
| REFACTOR | New rationalizations → add counters, build rationalization table, create red flags, re-test |
| Quality | Flowchart only if non-obvious, quick ref table, common mistakes, no narrative |
| Deploy | Commit and push, consider contributing PR |
Discovery Workflow
How future agents find your skill:
- Encounters problem ("tests are flaky")
- Finds SKILL (description matches)
- Scans overview (is this relevant?)
- Reads patterns (quick reference table)
- Loads example (only when implementing)
Optimize for this flow - put searchable terms early and often.
The Bottom Line
Creating skills IS TDD for process documentation.
Same Iron Law: No skill without failing test first.
Same cycle: RED (baseline) → GREEN (write skill) → REFACTOR (close loopholes).
Same benefits: Better quality, fewer surprises, bulletproof results.
If you follow TDD for code, follow it for skills. It's the same discipline applied to documentation.
