How to Build a Custom OpenClaw Skill

Introduction

OpenClaw skills are MCP (Model Context Protocol) servers that expose tools to the agent. When you build a skill, you are giving your agent new capabilities -- from accessing APIs to controlling hardware to processing files. Skills are the primary way to make your OpenClaw agent do things beyond conversation.

Prerequisites

• Node.js 18+ or Python 3.10+ installed
• Basic programming knowledge (TypeScript or Python recommended)
• A KiwiClaw account with an active agent for testing
• Familiarity with the OpenClaw architecture

Step-by-Step Instructions

Step 1: Understand the Skill Format

An OpenClaw skill is an MCP server that exposes one or more tools. Each tool has a name, description, input schema, and a handler function. The agent discovers available tools and decides when to call them based on the conversation context.

Step 2: Set Up Your Development Environment

Create a new project directory. If using TypeScript, initialize with npm init and install the MCP SDK. If using Python, set up a virtual environment and install the MCP Python package.

Step 3: Create the Skill Manifest

Define your skill's metadata: name, version, description, author, and the list of tools it provides. This manifest tells OpenClaw what your skill can do.

Step 4: Write Your Tool Handlers

Implement the functions for each tool. A tool handler receives input parameters and returns a result. For example, a weather skill might accept a city name and return the current forecast by calling a weather API.

Step 5: Test Locally

Run your skill locally and test it against your KiwiClaw agent. Install the skill using the dashboard's Skills page by pointing to your local server. Verify each tool works correctly.

Step 6: Publish to the Marketplace

When your skill is ready, submit it to the KiwiClaw Skills Marketplace. Our team reviews submissions for security and quality. Once approved, other users can install your skill. You can set it as free or paid.

Pro Tips

• Start with the Skill Creator -- This meta-skill helps your agent build other skills, generating boilerplate code for you.
• Keep tools focused -- Each tool should do one thing well. Multiple small tools are better than one complex tool.
• Handle errors gracefully -- Return informative error messages so the agent can explain what went wrong to the user.
• Add good descriptions -- The agent uses tool descriptions to decide when to call them. Clear, specific descriptions lead to better tool selection.

Frequently Asked Questions

What programming language can I use for OpenClaw skills?

OpenClaw skills are MCP servers, so you can use any language that supports the MCP protocol. Most skills are written in TypeScript or Python, but Go, Rust, and other languages work too.

Can I monetize my OpenClaw skill?

Yes. Publish your skill to the KiwiClaw marketplace and set a price. KiwiClaw handles payments, distribution, and reviews. You earn revenue every time someone installs your paid skill. See our publishing guide for details.

How are skills reviewed for security?

All marketplace submissions go through KiwiClaw's vetting process. We review the source code, check for malicious behavior, verify permissions, and test functionality before approving a skill for the marketplace.