| name | writing-skills |
| description | Guide for creating new skills for the Claude Code foundation. Trigger when the user wants to create a skill, add a command, or extend the foundation. |
| allowed-tools | ["Read","Write","Edit","Glob","Grep"] |
| context | fork |
Creating New Skills
Objective
Framework for creating quality skills for the Claude Code foundation, respecting the existing conventions and structure.
Skill structure
.claude/skills/<skill-name>/
└── SKILL.md
SKILL.md format
---
name: my-skill
description: Clear description of the skill. Trigger when [activation context].
allowed-tools:
- Read
- Write
- Edit
- Bash
- Glob
- Grep
context: fork
---
[Clear description of what the skill does]
[Detailed instructions, structured in steps]
[Expected output format]
[Mandatory rules for the skill]
Available Frontmatter Fields (Claude Code 2.1+)
All fields available in the YAML frontmatter of a skill:
| Field | Required | Description |
|---|
name | No | Skill name (default: folder name). Lowercase, digits, hyphens (max 64 chars) |
description | Recommended | What the skill does and when to use it. Claude uses this to decide when to load the skill |
allowed-tools | No | Tools authorized without permission prompt |
context | No | fork for execution in an isolated sub-agent |
model | No | Model to use: sonnet, opus, haiku, inherit (default: inherits from context) |
agent | No | Sub-agent type when context: fork (Explore, Plan, general-purpose, or custom agent) |
disable-model-invocation | No | true = manual invocation only (Claude cannot auto-load). Default: false |
user-invocable | No | false = invisible in the / menu (background skills). Default: true |
argument-hint | No | Autocompletion hint shown in the / menu. E.g.: [issue-number] or [filename] [format] |
hooks | No | Hooks scoped to the skill lifecycle (PreToolUse, PostToolUse, Stop) |
Variable substitutions
| Variable | Description |
|---|
$ARGUMENTS | All arguments passed to the skill |
$ARGUMENTS[N] | Argument by index (0-based) |
$N | Shortcut for $ARGUMENTS[N] |
${CLAUDE_SESSION_ID} | Current session ID |
Dynamic context injection
Use the backtick-bang syntax to inject live data:
- Example:
! followed by backtick then gh pr diff then backtick
- The command runs BEFORE Claude sees the content
- The result replaces the placeholder
Example:
## PR Context
- Diff: !`gh pr diff`
- Files: !`gh pr diff --name-only`
Frontmatter best practices
- SKILL.md < 500 lines (move detail to reference files via
supporting files)
- Description budget: 15,000 chars max (variable
SLASH_COMMAND_TOOL_CHAR_BUDGET)
- Supporting files:
examples/, scripts/, reference.md in the skill folder
- Use
disable-model-invocation: true for skills that should only be launched manually (e.g.: commit, PR, plan)
- Use
user-invocable: false for context/background skills that Claude loads automatically (state-management, api-mocking)
- Use
model: sonnet for complex skills requiring deep reasoning (debug, security, TDD, perf)
- Use
argument-hint to guide the user on the expected parameters
Skill quality checklist
Structure
[ ] Valid YAML frontmatter (name, description, allowed-tools, context)
[ ] kebab-case name
[ ] Description with trigger context
[ ] Minimal necessary tools (principle of least privilege)
[ ] context: fork (isolation)
Content
[ ] Clear objective in 1-2 sentences
[ ] Instructions structured as numbered steps
[ ] Relevant code examples
[ ] Expected output with template
[ ] Explicit rules and constraints
[ ] ASCII diagram if complex workflow
Quality
[ ] Actionable (not just informative)
[ ] Specific (not generic)
[ ] Testable (verifiable results)
[ ] Standalone (no dependency on other skills)
[ ] Consistent with the foundation's conventions
Foundation conventions
Naming
| Type | Convention | Examples |
|---|
| Dev skills | dev-* | dev-tdd, dev-debug, dev-api |
| QA skills | qa-* | qa-review, qa-security |
| Ops skills | ops-* | ops-docker, ops-ci |
| Doc skills | doc-* | doc-generate, doc-changelog |
| Growth skills | growth-* | growth-seo, growth-cro |
| Biz skills | biz-* | biz-model, biz-mvp |
| Legal skills | legal-* | legal-rgpd |
| Data skills | data-* | data-pipeline |
| Workflow skills | work-* | work-explore, work-plan |
| Meta skills | Descriptive name | parallel-agents, session-handoff |
Content patterns
1. ASCII workflow diagram (if applicable)
2. Numbered steps with subsections
3. Tables for quick references
4. Code blocks with specified language
5. "Expected output" section with template
6. "Rules" section with IMPORTANT/NEVER/YOU MUST
Tools by skill type
| Skill type | Recommended tools |
|---|
| Read-only (audit, review) | Read, Glob, Grep |
| Development | Read, Write, Edit, Bash, Glob, Grep |
| Infrastructure | Read, Write, Edit, Bash, Glob, Grep |
| Documentation | Read, Write, Edit, Glob, Grep |
| Analysis | Read, Glob, Grep |
Also create the associated files
Command (optional)
.claude/commands/<domain>/<name>.md
Format: detailed prompt with $ARGUMENTS, workflow, expected output, related agents.
Agent (optional)
.claude/agents/<name>.md
Format: YAML frontmatter with model, permissionMode, disallowedTools, skills, hooks.
Rule (optional)
.claude/rules/<name>.md
Format: frontmatter with paths, contextual rules per file type.
Creation workflow
1. IDENTIFY the need (which problem does this skill solve?)
2. NAME according to conventions (domain-action)
3. DEFINE the necessary tools (principle of least privilege)
4. WRITE the SKILL.md with the template
5. CREATE the associated command if manual invocation is needed
6. CREATE the associated agent if isolated execution is needed
7. TEST the skill (invoke it and verify the result)
8. DOCUMENT in CLAUDE.md (skills table)
Rules
- One skill = one single responsibility
- Description with mandatory trigger context
- Minimal tools (no Write if the skill doesn't modify anything)
- Always use
context: fork for isolation
- Concrete examples, no abstract theory
- Expected output clearly defined
