| name | writing-skills |
| description | Creates and improves Claude Code skills following the official Anthropic spec and house standards. Use when creating new skills, modifying existing skills, or improving skill quality. Use when user says "create a skill", "write a skill", "add capability". Use when a repeated pattern should become reusable. |
Writing Skills
Overview
Writing skills IS structured documentation creation for process guidance.
Analyze requirements clearly, design skill structure thoughtfully, implement with precision, validate functionality, and iterate based on feedback.
Core principle: Clear requirements and structured design lead to effective skills that truly guide agent behavior.
Task Initialization (MANDATORY)
Follow task initialization protocol.
Tasks:
0. Fetch latest official skill spec
- Analyze requirements
- Design skill structure
- Implement SKILL.md
- Add references (if needed)
- Validate structure
- REFACTOR - quality review
- Test with real usage
Announce: "Created 8 tasks (0–7). Starting execution..."
Skill Creation Process
| Phase | Focus | What You Do |
|---|
| Requirements | Understanding | Analyze what capability is needed and why |
| Design | Structure | Plan skill organization, triggers, and content |
| Implementation | Creation | Write skill following design and best practices |
| Validation | Testing | Verify skill works correctly in real scenarios |
| Improvement | Refinement | Iterate based on feedback and usage patterns |
Task 0: Fetch Latest Official Spec
Goal: Pull the current Anthropic skill spec before designing — never trust cached memory.
Action:
Skill tool: fetching-claude-docs
component: skill
question: "frontmatter fields (name, description), description trigger
format, SKILL.md structure, references/ progressive disclosure,
skill activation"
Verification: Received YAML with source: https://code.claude.com/docs/en/skills.md and non-empty spec_excerpt. Use as authoritative reference; if any rule in this SKILL conflicts with the fetched spec, the fetched spec wins.
Task 1: Analyze Requirements
Goal: Understand what skill to create and why. Present full analysis to user for confirmation.
Analyze and answer ALL questions below:
- What capability does this skill teach?
- What triggers should activate it? (specific phrases, symptoms)
- Is this reusable across projects, or project-specific?
- Does a similar skill already exist?
- What are the key design decisions? List alternatives considered and chosen approach with rationale.
External search (optional): If claude-skills-mcp available, search for existing community skills to adapt.
MANDATORY: Present analysis to user. Display ALL answers above in full detail, then ask user to confirm before proceeding. Do NOT summarize into a single sentence. Do NOT skip to next task without explicit user approval.
Verification: User has reviewed the full analysis and confirmed the direction.
Task 2: Design Skill Structure
Goal: Plan the skill's organization, triggers, and content.
Before drafting, walk through prompt-design-principles.md:
- 5-skeleton framework — every skill needs Role, Scope, Workflow, Standards, Completion. Confirm each has concrete content planned.
- Failure-mode reverse engineering — the Red Flags section should reflect specific failures you've observed or can predict, not generic warnings.
- Conditional dispatch — list task variants the skill handles and per-variant behavior before writing absolute rules.
- Creative-constraint balance — explicitly decide what can vary (form, solution options) vs. what must be fixed (process, verification, tool order).
- Completion semantics — the final task must have a binary pass/fail check, not a narrative "done" signal.
Design considerations:
- What specific capability does this skill provide?
- When should the skill be triggered? (specific phrases, symptoms)
- What are the key tasks and workflow steps?
- What supporting materials are needed? (references, examples)
Structure planning:
- Clear trigger conditions in description
- Logical task sequence
- Verification criteria for each task
- Red flags and common mistakes
Verification: Have clear design plan with triggers, tasks, and structure defined.
Task 3: Implement SKILL.md
Goal: Create the skill following the design plan and best practices.
Skill Structure
skill-name/
├── SKILL.md # Required (<300 lines)
├── scripts/ # Optional: executable tools
└── references/ # Optional: detailed docs
If the skill includes scripts: Use project's primary language if detectable (check package.json, go.mod, Cargo.toml, pyproject.toml, etc.); default to Python when unclear. Read cross-platform-scripts.md for mandatory cross-platform rules (paths, shell commands, line endings).
Naming Convention
Gerund form (verb + -ing): writing-skills, processing-pdfs
- Lowercase, hyphens, numbers only
- Max 64 characters
- Avoid:
helper, utils, anthropic, claude
SKILL.md Format
See references/spec.md for full frontmatter specification (fields, arguments, model selection, context:fork).
Context and Agent Selection
| Use Case | context | agent | Rationale |
|---|
| Inline knowledge (conventions, patterns) | (none) | (none) | Runs in main conversation, Claude applies alongside current context |
| Analysis or exploration task | fork | Explore | Isolated context, read-only tools, prevents context pollution |
| Planning task | fork | Plan | Isolated context, research-focused |
| Task with side effects (deploy, commit) | fork | (none) | Isolated from main conversation, uses general-purpose agent |
| Default for most skills | (none) | (none) | Runs inline, cheapest, fastest |
When to use context: fork:
- Skill generates large output that would pollute main context
- Skill is a self-contained task (not reference material)
- Skill needs different tools than the main conversation
When NOT to use context: fork:
- Skill provides conventions or guidelines (needs main context to apply them)
- Skill content is reference material for ongoing work
- Skill needs access to conversation history
Key rules:
- Name: gerund form, lowercase, hyphens only, max 64 chars
- Description:
[What it does]. [Key capabilities]. Use when [triggers]. — third person, does not enumerate workflow steps
- Body: < 300 lines, detailed content goes to
references/
- Parallel tool calls: when skill tasks involve independent reads, searches, or writes, explicitly state "run these tool calls in parallel" so the agent fans out instead of serializing
Body Structure
Essential sections: Overview, Tasks (with verification each), References. Add only when they earn their place: Routing (only when the skill hands off to other skills — omit if Handoff/Next would be "none"), Task Initialization (multi-step flows), Red Flags / Common Rationalizations (real rationalization risks). No flowchart required. See references/patterns.md for the template.
Verification
Can answer YES to all:
Task 4: Add References (if needed)
Goal: Move detailed content to references/ for progressive disclosure.
When to extract:
- API documentation (100+ lines)
- Detailed examples
- Edge case handling
- Background theory
Keep in SKILL.md:
- Core workflow
- Task definitions
- Red Flags and Rationalizations
- Quick reference tables
Verification: SKILL.md is < 300 lines. All detailed content has a reference link.
Task 5: Validate Structure
Goal: Verify skill structure is correct.
Use scripts/validate_skill.py to run automated validation:
python3 "${CLAUDE_SKILL_DIR}/scripts/validate_skill.py" <path/to/skill>
Manual checklist if script unavailable:
Verification: Validation passes with no errors.
Task 6: REFACTOR - Quality Review
Goal: Have skill reviewed by skill-reviewer subagent.
Agent tool:
- subagent_type: "rcc:skill-reviewer"
- prompt: "Review skill at [path/to/skill]"
Interpret YAML output:
pass: true → Proceed to Task 7pass: false → Fix all issues listed, re-run reviewer, repeat until pass: true
This is the improvement phase: Address issues and refine quality based on reviewer feedback.
Verification: skill-reviewer returns YAML with pass: true.
Task 7: Test with Real Usage
Goal: Verify skill works in practice.
Process:
- Start new Claude Code session (fresh context)
- Trigger skill naturally - use words from description, don't mention skill name
- Verify skill activates
- Verify agent follows instructions correctly
- Run original pressure scenario WITH skill - agent should now comply
Verification:
- Skill activates when triggered naturally
- Agent follows skill instructions
- Agent passes pressure scenario that failed in baseline
Red Flags - STOP
These thoughts mean you're rationalizing. STOP and reconsider:
- "Skip requirements analysis, I know what's needed"
- "Description can enumerate the workflow steps"
- "300 lines is too restrictive"
- "Skip reviewer, the skill is obviously good"
- "Testing is overkill for a simple skill"
- "I'll add Red Flags later"
- "Task list is too bureaucratic"
All of these mean: You're about to create a weak skill. Follow the process.
Common Rationalizations
| Excuse | Reality |
|---|
| "I know what agents need" | You know what YOU think they need. Baseline reveals actual failures. |
| "Baseline testing takes too long" | 15 min baseline saves hours debugging weak skill. |
| "Description only needs triggers" | Description = what it does + when to load. Body = how. Claude picks among 100+ skills by capability statement. |
| "More content = better skill" | More content = more to skip. Concise + references = better. |
| "Red Flags are negative" | Red Flags prevent rationalization. Essential for discipline skills. |
| "TaskCreate is overhead" | TaskCreate prevents skipping steps. The overhead IS the value. |
References
