skillcraft

# Skills Development Create skills that follow the [Agent Skills specification](https://agentskills.io/specification)—an open format supported by Claude Code, Cursor, VS Code, GitHub Copilot, Codex, and other agent products. ## Workflow 1. **Discovery** — Understand what the skill should do 2. **Archetype Selection** — Choose the best pattern 3. **Initialization** — Create skill structure 4. **Customization** — Tailor to specific needs 5. **Validation** — Verify quality before committing ## Stage 1: Discovery Ask about the skill: - What problem does this skill solve? - What are the main capabilities? - What triggers should invoke it? (phrases users would say) - Where should it live? (personal, project, or plugin) - Is it for use within a Claude plugin? If so, load the `/claude-craft` and `/claude-plugins` skills. ## Stage 2: Archetype Selection | Archetype | Use When | Example | | ------------------------ | -------------------------------------- | --------------------------------------- | | **simple** | Basic skill without scripts | Quick reference, style guide | | **api-wrapper** | Wrapping external APIs | GitHub API, Stripe API | | **document-processor** | Working with file formats | PDF extractor, Excel analyzer | | **dev-workflow** | Automating development tasks | Git workflow, project scaffolder | | **research-synthesizer** | Gathering and synthesizing information | Competitive analysis, literature review | ## Stage 3: Directory Structure ``` skill-name/ ├── SKILL.md # Required: instructions + metadata ├── scripts/ # Optional: executable code ├── references/ # Optional: documentation └── assets/ # Optional: templates, resources ``` ## Stage 4: Frontmatter Schema ```yaml --- name: skill-name description: "What it does and when to use it. Include trigger keywords." version: 1.0.0 # optional, recommended license: Apache-2.0 # optional compatibility: Requires git and jq # optional metadata: # optional author: your-org category: development tags: [testing, automation] --- ``` | Field | Required | Constraints | | --------------- | -------- | ----------------------------------------------------------- | | `name` | Yes | 2-64 chars, lowercase/numbers/hyphens, must match directory | | `description` | Yes | 10-1024 chars, quoted, describes what + when | | `version` | No | Semantic version (MAJOR.MINOR.PATCH) | | `license` | No | License name or reference | | `compatibility` | No | 1-500 chars, environment requirements | | `metadata` | No | Object for custom fields | **Important**: - Always wrap `description` in double quotes — values containing colons, commas, or special characters can break YAML parsing otherwise. - Platform-specific fields (e.g., Claude's `allowed-tools`, `user-invocable`) should be added per-platform. Load the `/claude-craft` skill for Claude-specific fields. ### Custom Frontmatter Custom fields **must** be nested under `metadata`: ```yaml --- name: my-skill description: "..." metadata: author: your-org version: "1.0" category: development tags: [typescript, testing] --- ``` Top-level custom fields are not allowed and may cause parsing errors. ### Description Formula **[WHAT] + [WHEN] + [TRIGGERS]** ```yaml description: "Extracts text and tables from PDF files, fills forms, merges documents. Use when working with PDF files or document extraction." ``` **Checklist:** - [ ] Explains WHAT (capabilities) - [ ] States WHEN (trigger conditions) - [ ] Includes 3-5 trigger KEYWORDS - [ ] Uses third-person voice - [ ] Under 200 words ## Stage 5: Validation ### Validation Checklist #### A. YAML Frontmatter - [ ] Opens with `---` on line 1, closes with `---` - [ ] `name` and `description` present (required) - [ ] `description` wrapped in double quotes - [ ] Uses spaces, not tabs - [ ] Special characters quoted #### B. Naming - [ ] Lowercase, numbers, hyphens only (1-64 chars) - [ ] Matches parent directory name - [ ] No `--`, leading/trailing hyphens - [ ] No `anthropic` or `claude` in name - [ ] Does not collide with a built-in slash command #### C. Description Quality - [ ] WHAT: Explains capabilities - [ ] WHEN: States "Use when..." conditions - [ ] TRIGGERS: 3-5 keywords users would say - [ ] Third-person voice (not "I can" or "you can") #### D. Structure - [ ] SKILL.md under 500 lines - [ ] All referenced files exist - [ ] No TODO/placeholder markers - [ ] Progressive disclosure (details in `references/`) - [ ] No `` <bang>`command` `` preprocessing patterns (use `<bang>` instead of literal `!`) ### Report Format ```markdown # Skill Check: {skill-name} **Status**: PASS | WARNINGS | FAIL **Issues**: {critical} critical, {warnings} warnings ## Critical (must fix) 1. {issue with fix} ## Warnings (should fix) 1. {issue with fix} ## Strengths - {what's done well} ``` ## Core Principles ### Concise is key Context window is shared. Only include what the agent doesn't already know. Challenge each paragraph—does it justify its token cost? ### Third-person descriptions Descriptions inject into system prompt: - "Extracts text from PDFs" - "I can help you extract text from PDFs" ### Progressive disclosure Keep SKILL.md under 500 lines. Move details to: - `references/` - Detailed docs, API references - `scripts/` - Executable utilities (code never enters context) - `assets/` - Templates, data files ### Preprocessing safety SKILL.md files are preprocessed by Claude Code — `` <bang>`command` `` syntax executes at load time, even inside code fences. When documenting this syntax in SKILL.md, use `<bang>` as a stand-in for `!`. Reference files and EXAMPLES.md are not preprocessed, so literal `!` is safe there. Skills that intentionally preprocess should declare `metadata.preprocess: true`. Run `/skillcheck` to lint for unintentional preprocessing patterns. Token loading: 1. **Metadata** (~100 tokens): name + description at startup 2. **Instructions** (<5000 tokens): SKILL.md body when activated 3. **Resources** (as needed): files loaded only when referenced ### Degrees of freedom Match instruction specificity to task requirements: - **High freedom** (text): Multiple valid approaches, use judgment - **Medium freedom** (pseudocode): Preferred pattern with variation allowed - **Low freedom** (scripts): Exact sequence required, no deviation See [patterns.md](references/patterns.md) for detailed examples. ## Naming Requirements - Lowercase letters, numbers, hyphens only - Cannot start/end with hyphen or contain `--` - Must match parent directory name - Cannot contain `anthropic` or `claude` - Must not collide with built-in slash commands (`/help`, `/status`, `/config`, `/compact`, `/review`, `/model`, `/init`, `/login`, `/logout`, `/doctor`, `/clear`, `/mcp`, `/memory`, `/permissions`, `/terminal-setup`, `/vim`, `/cost`, `/bug`). Built-in commands take precedence — a skill with a colliding name will be unreachable via slash invocation. **Recommended**: Gerund form (`processing-pdfs`, `reviewing-code`) ## Platform-Specific Guidance Skills are cross-platform, but each tool has specific implementation details: - **Claude Code**: Load the `/claude-craft` skill for Claude-specific skill authoring - **Codex CLI**: See [codex.md](references/codex.md) for discovery paths, `$skill-name` invocation See [implementations.md](references/implementations.md) for storage paths and [invocations.md](references/invocations.md) for activation patterns. ## References - [steps-pattern.md](references/steps-pattern.md) - Composable skill workflows with dependencies - [patterns.md](references/patterns.md) - Degrees of freedom, script design, variant organization - [best-practices.md](references/best-practices.md) - Community patterns, testing strategies - [quick-reference.md](references/quick-reference.md) - Fast checklist and one-liners - [implementations.md](references/implementations.md) - Per-tool storage paths - [invocations.md](references/invocations.md) - How tools activate skills - [compatibility.md](references/compatibility.md) - Path compatibility matrix ## External Resources - [Agent Skills Specification](https://agentskills.io/specification) - [Best Practices Guide](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices) - [skills-ref Validation Library](https://github.com/agentskills/agentskills/tree/main/skills-ref)