Building Custom OpenClaw Skills: A Developer's Guide

OpenClaw ships with 50+ bundled skills and the ClawHub marketplace hosts over 5,700 community-built options. But the real power comes when you build skills tailored to your exact workflows. Here is how.

What is a Skill?

A skill is a directory that teaches OpenClaw how to perform a specific task. At minimum, it contains one file: SKILL.md — a natural language instruction file that tells the agent what the skill does, when to use it, and how it works.

Skills can be as simple as a text file with prompts or as complex as a full Node.js module with API integrations, database queries, and external service calls.

Skill Architecture

Every skill lives in its own directory with this basic structure:

my-skill/
  SKILL.md          # Required: natural language instructions
  index.ts          # Optional: code module for complex logic
  package.json      # Optional: dependencies for code modules
  config.json       # Optional: configurable parameters

The SKILL.md file is the heart of every skill. Write clear, natural language instructions explaining what the skill does, when it should be triggered, and what steps it should follow. No rigid schemas — just clear communication.

When to Build Custom Skills

Build a custom skill when:

• Generic skills do not fit — Your workflow has specific requirements that bundled skills cannot handle
• Deep integration needed — You need to connect to a specific internal API, database, or service
• Business logic is complex — Multi-step workflows with conditional branching, approvals, or data transformations
• Security requirements — You need control over exactly how credentials are handled and data flows

Do not build when bundled skills can compose to solve your problem. OpenClaw excels at combining multiple skills in a single workflow, and composed solutions require less maintenance.

Building a Simple Skill

A skill that summarizes daily sales from your database:

SKILL.md:

# Daily Sales Summary

## When to use
When the user asks for a sales summary, daily sales report, or revenue update.

## What to do
1. Query the sales database for today's orders
2. Calculate total revenue, order count, and average order value
3. List the top 5 products by revenue
4. Format as a clean summary suitable for messaging apps

This instruction-only skill leverages OpenClaw's built-in database and formatting capabilities. No code required.

Building an API-Integrated Skill

For skills that need to call external APIs, add a code module:

The code module handles API authentication, request formatting, error handling, and response parsing. The SKILL.md file tells the agent when to invoke the code and how to present results to the user.

Testing Skills

Always test skills in a sandboxed environment before production deployment:

1. Unit test the code module in isolation with mock API responses
2. Integration test with the real API in a staging environment
3. Conversation test by interacting with the skill through your messaging app
4. Edge case test with malformed inputs, API failures, and timeout scenarios

Security Review

Every custom skill should be reviewed for:

• Credential exposure — API keys should be in environment variables, never in code
• Data exfiltration — Skills should not send data to unauthorized endpoints
• Command injection — User inputs should be sanitized before shell execution
• Prompt injection — Skill instructions should be resistant to adversarial inputs

Publishing to ClawHub

If your skill solves a common problem, consider publishing it to ClawHub. The marketplace supports free and paid skills ($10-$200 depending on complexity). Early publishers are building significant passive income from quality skills.

When to Hire Professionals

Simple instruction-only skills are easy to build. But production-grade skills with API integrations, error handling, security review, and ongoing maintenance require engineering discipline. ECOSIRE's custom skills development service handles the full lifecycle: workflow analysis, architecture, development, testing, and deployment.

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Need custom OpenClaw skills for your business? Explore our skills development service or contact us to discuss your workflows.