Introduction
# Skillcraft — OpenClaw Skill Designer
An opinionated guide for creating OpenClaw skills. Focuses on **OpenClaw-specific integration** — message routing, cron scheduling, memory persistence, channel formatting, frontmatter gating — not generic programming advice.
**Docs:** <https://docs.openclaw.ai/tools/skills> · <https://docs.openclaw.ai/tools/creating-skills>
## Model Notes
This skill is written for frontier-class models (Opus, Sonnet). If you're running a cheaper model and find a stage underspecified, expand it yourself — the design sequence is a scaffold, not a script. Cheaper models should:
- Read the pattern files in `{baseDir}/patterns/` more carefully before architecting - Spend more time on Stage 2 (capability discovery) — enumerate OpenClaw features explicitly - Be more methodical in Stage 4 (spec) — write out the full structure before implementing - Consult <https://docs.openclaw.ai> when unsure about any OpenClaw feature
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## The Design Sequence
### Stage 0: Inventory (Extraction Only)
Skip if building from scratch. Use when packaging existing functionality (scripts, TOOLS.md sections, conversation patterns, repeated instructions) into a skill.
Gather what exists, where it lives, what works, what's fragile. Then proceed to Stage 1.
### Stage 1: Problem Understanding
Work through with the user:
1. **What does this skill do?** (one sentence) 2. **When should it load?** Example phrases, mid-task triggers, scheduled triggers 3. **What does success look like?** Concrete outcomes per example
### Stage 2: Capability Discovery
#### Generalisability
Ask early: **Is this for your setup, or should it work on any OpenClaw instance?**
| Choice | Implications | |--------|-------------| | **Universal** | Generic paths, no local assumptions, ClawHub-ready | | **Particular** | Can reference local skills, tools, workspace config |
#### Skill Synergy (Particular Only)
Scan `<available_skills>` from the system prompt for complementary capabilities. Read promising skills to understand composition opportunities.
#### OpenClaw Features
Review the docs with the skill's needs in mind. Think compositionally — OpenClaw's primitives combine in powerful ways. Key docs to check:
| Need | Doc | |------|-----| | Messages | `/concepts/messages` | | Cron/scheduling | `/automation/cron-jobs` | | Subagents | `/tools/subagents` | | Browser | `/tools/browser` | | Canvas UI | `/tools/` (canvas) | | Node devices | `/nodes/` | | Slash commands | `/tools/slash-commands` |
See `{baseDir}/patterns/composable-examples.md` for inspiration on combining these.
### Stage 3: Architecture
Based on Stages 1–2, identify which patterns apply:
| If the skill... | Pattern | |-----------------|---------| | Wraps a CLI tool | `{baseDir}/patterns/cli-wrapper.md` | | Wraps a web API | `{baseDir}/patterns/api-wrapper.md` | | Monitors and notifies | `{baseDir}/patterns/monitor.md` |
Load all that apply and synthesise. Most skills combine patterns.
**Script vs. instructions split:** Scripts handle deterministic mechanics (API calls, data gathering, file processing). SKILL.md instructions handle judgment (interpreting results, choosing approaches, composing output). The boundary is: could a less intelligent system do this reliably? If yes → script.
### Stage 4: Design Specification
Present proposed architecture for user review:
1. **Skill structure** — files and directories 2. **SKILL.md outline** — sections and key content 3. **Components** — scripts, modules, wrappers 4. **State** — stateless, session-stateful, or persistent (and where it lives) 5. **OpenClaw integration** — which features, how they interact 6. **Secrets** — env vars, keychain, config file (document in setup section, never hardcode)
**State locations:** - `<workspace>/memory/` — user-facing context - `{baseDir}/state.json` — skill-internal state (travels with skill) - `<workspace>/state/<skill>.json` — skill state in common workspace area
If extracting: include migration notes (what moves, what workspace files need updating).
**Validate:** Does it handle all Stage 1 examples? Any contradictions? Edge cases?
Iterate until the user is satisfied. This is where design problems surface cheaply.
### Stage 5: Implementation
**Default: same-session.** Work through the spec with user review at each step. Reserve subagent handoff for complex script subcomponents only — SKILL.md and integration logic stay in the main session.
1. Create skill directory + SKILL.md skeleton (frontmatter + sections) 2. Scripts (if any) — get them working and tested 3. SKILL.md body — complete instructions 4. Test against Stage 1 examples
If extracting: update workspace files, clean up old locations, verify standalone operation.
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## Crafting the Frontmatter
The frontmatter determines discoverability and gating. Format follows the [AgentSkills](https://agentskills.io) spec with OpenClaw extensions.
```yaml --- name: my-skill description: [description optimised for discovery — see below] homepage: https://github.com/user/repo # optional metadata: {"openclaw":{"emoji":"🔧","requires":{"bins":["tool"],"env":["API_KEY"]},"primaryEnv":"API_KEY","install":[...]}} --- ```
**Critical:** `metadata` must be a **single-line** JSON object (parser limitation).
### Description — Write for Discovery
The description determines whether the skill gets loaded. Include: - **Core capability** — what it does - **Trigger keywords** — terms users would say - **Contexts** — situations where it applies
Test: would the agent select this skill for each of your Stage 1 example phrases?
### Frontmatter Keys
| Key | Purpose | |-----|---------| | `name` | Skill identifier (required) | | `description` | Discovery text (required) | | `homepage` | URL for docs/repo | | `user-invocable` | `true`/`false` — expose as slash command (default: true) | | `disable-model-invocation` | `true`/`false` — exclude from model prompt (default: false) | | `command-dispatch` | `tool` — bypass model, dispatch directly to a tool | | `command-tool` | Tool name for direct dispatch | | `command-arg-mode` | `raw` — forward raw args to tool |
### Metadata Gating
OpenClaw filters skills at load time using `metadata.openclaw`:
| Field | Effect | |-------|--------| | `always: true` | Skip all gates, always load | | `emoji` | Display in macOS Skills UI | | `os` | Platform filter (`darwin`, `linux`, `win32`) | | `requires.bins` | All must exist on PATH | | `requires.anyBins` | At least one must exist | | `requires.env` | Env var must exist or be in config | | `requires.config` | Config paths must be truthy | | `primaryEnv` | Maps to `skills.entries.<name>.apiKey` | | `install` | Installer specs for auto-setup (brew/node/go/uv/download) |
**Sandbox note:** `requires.bins` checks the **host** at load time. If sandboxed, the binary must also exist inside the container.
### Token Budget
Each eligible skill adds ~97 chars + name + description + location path to the system prompt. Keep descriptions informative but not bloated — every character costs tokens on every turn.
### Install Specs
```json "install": [ {"id": "brew", "kind": "brew", "formula": "tap/tool", "bins": ["tool"], "label": "Install via brew"}, {"id": "npm", "kind": "node", "package": "tool", "bins": ["tool"]}, {"id": "uv", "kind": "uv", "package": "tool", "bins": ["tool"]}, {"id": "go", "kind": "go", "package": "github.com/user/tool@latest", "bins": ["tool"]}, {"id": "dl", "kind": "download", "url": "https://...", "archive": "tar.gz"} ] ```
## Path Conventions
| Token | Meaning | |-------|---------| | `{baseDir}` | This skill's directory (OpenClaw resolves at runtime) | | `<workspace>/` | Agent's workspace root |
- Use `{baseDir}` for skill-internal references (scripts, state, patterns) - Use `<workspace>/` for workspace files (TOOLS.md, memory/, etc.) - Never hardcode absolute paths — workspaces are portable - For subagent scenarios, include path context in the task description (sandbox mounts differ)
## References
- Pattern files: `{baseDir}/patterns/` (cli-wrapper, api-wrapper, monitor, composable-examples) - OpenClaw docs: <https://docs.openclaw.ai/tools/skills> - ClawHub: <https://clawhub.com>