Skill Creator

Skill Creator

This skill provides guidance for creating effective skills. Windows PowerShell equivalents for the Unix shell commands used in examples are in references/windows.md.

About Skills

Skills are modular, self-contained packages that extend OpenHands's capabilities by providing specialized knowledge, workflows, and tools. Think of them as "onboarding guides" for specific domains or tasks—they transform OpenHands from a general-purpose agent into a specialized agent equipped with procedural knowledge that no model can fully possess.

What Skills Provide

1. Specialized workflows - Multi-step procedures for specific domains
2. Tool integrations - Instructions for working with specific file formats or APIs
3. Domain expertise - Company-specific knowledge, schemas, business logic
4. Bundled resources - Scripts, references, and assets for complex and repetitive tasks

Anatomy of a Skill

Every skill consists of a required SKILL.md file and optional bundled resources:

skill-name/
├── SKILL.md (required)
│   ├── YAML frontmatter metadata (required)
│   │   ├── name: (required)
│   │   └── description: (required)
│   └── Markdown instructions (required)
└── Bundled Resources (optional)
    ├── scripts/          - Executable code (Python/Bash/etc.)
    ├── references/       - Documentation intended to be loaded into context as needed
    └── assets/           - Files used in output (templates, icons, fonts, etc.)

SKILL.md (required)

Metadata Quality: The name and description in YAML frontmatter determine when OpenHands will use the skill. Be specific about what the skill does and when to use it. Use the third-person (e.g. "This skill should be used when..." instead of "Use this skill when...").

Slash commands vs keyword triggers: SKILL.md frontmatter supports an optional triggers: field for keyword-based activation (e.g., triggers: [docker, container]). For slash commands (e.g., /codereview, /init), prefer creating a commands/command-name.md file in the plugin's commands/ directory instead of using slash triggers in SKILL.md. Slash triggers still work for backward compatibility but are deprecated in favor of the commands/ approach. See the Plugins guide for details.

Bundled Resources (optional)

Scripts (scripts/)

Executable code (Python/Bash/etc.) for tasks that require deterministic reliability or are repeatedly rewritten.

• When to include: When the same code is being rewritten repeatedly or deterministic reliability is needed
• Example: scripts/rotate_pdf.py for PDF rotation tasks
• Benefits: Token efficient, deterministic, may be executed without loading into context
• Note: Scripts may still need to be read by OpenHands for patching or environment-specific adjustments
• Python dependencies: Use uv instead of pip or pip3 for all Python dependency installs. uv is cross-platform, faster, and avoids the pip/pip3 naming inconsistency across environments. Example: uv venv .venv --quiet && uv pip install --quiet <package>

References (references/)

Documentation and reference material intended to be loaded as needed into context to inform OpenHands's process and thinking.

• When to include: For documentation that OpenHands should reference while working
• Examples: references/finance.md for financial schemas, references/mnda.md for company NDA template, references/policies.md for company policies, references/api_docs.md for API specifications
• Use cases: Database schemas, API documentation, domain knowledge, company policies, detailed workflow guides
• Benefits: Keeps SKILL.md lean, loaded only when OpenHands determines it's needed
• Best practice: If files are large (>10k words), include grep search patterns in SKILL.md
• Avoid duplication: Information should live in either SKILL.md or references files, not both. Prefer references files for detailed information unless it's truly core to the skill—this keeps SKILL.md lean while making information discoverable without hogging the context window. Keep only essential procedural instructions and workflow guidance in SKILL.md; move detailed reference material, schemas, and examples to references files.

Assets (assets/)

Files not intended to be loaded into context, but rather used within the output OpenHands produces.

• When to include: When the skill needs files that will be used in the final output
• Examples: assets/logo.png for brand assets, assets/slides.pptx for PowerPoint templates, assets/frontend-template/ for HTML/React boilerplate, assets/font.ttf for typography
• Use cases: Templates, images, icons, boilerplate code, fonts, sample documents that get copied or modified
• Benefits: Separates output resources from documentation, enables OpenHands to use files without loading them into context

Progressive Disclosure Design Principle

Skills use a three-level loading system to manage context efficiently:

1. Metadata (name + description) - Always in context (~100 words)
2. SKILL.md body - When skill triggers (<5k words)
3. Bundled resources - As needed by OpenHands (Unlimited*)

*Unlimited because scripts can be executed without reading into context window.

Skill Creation Process

To create a skill, follow the "Skill Creation Process" in order, skipping steps only if there is a clear reason why they are not applicable.

Step 1: Understanding the Skill with Concrete Examples

Skip this step only when the skill's usage patterns are already clearly understood. It remains valuable even when working with an existing skill.

To create an effective skill, clearly understand concrete examples of how the skill will be used. This understanding can come from either direct user examples or generated examples that are validated with user feedback.

For example, when building an image-editor skill, relevant questions include:

• "What functionality should the image-editor skill support? Editing, rotating, anything else?"
• "Can you give some examples of how this skill would be used?"
• "I can imagine users asking for things like 'Remove the red-eye from this image' or 'Rotate this image'. Are there other ways you imagine this skill being used?"
• "What would a user say that should trigger this skill?"

To avoid overwhelming users, avoid asking too many questions in a single message. Start with the most important questions and follow up as needed for better effectiveness.

Conclude this step when there is a clear sense of the functionality the skill should support.

Step 2: Planning the Reusable Skill Contents

To turn concrete examples into an effective skill, analyze each example by:

1. Considering how to execute on the example from scratch
2. Identifying what scripts, references, and assets would be helpful when executing these workflows repeatedly

Example: When building a pdf-editor skill to handle queries like "Help me rotate this PDF," the analysis shows:

1. Rotating a PDF requires re-writing the same code each time
2. A scripts/rotate_pdf.py script would be helpful to store in the skill

Example: When designing a frontend-webapp-builder skill for queries like "Build me a todo app" or "Build me a dashboard to track my steps," the analysis shows:

1. Writing a frontend webapp requires the same boilerplate HTML/React each time
2. An assets/hello-world/ template containing the boilerplate HTML/React project files would be helpful to store in the skill

Example: When building a big-query skill to handle queries like "How many users have logged in today?" the analysis shows:

1. Querying BigQuery requires re-discovering the table schemas and relationships each time
2. A references/schema.md file documenting the table schemas would be helpful to store in the skill

To establish the skill's contents, analyze each concrete example to create a list of the reusable resources to include: scripts, references, and assets.

Step 3: Create Skill Structure

Create the skill directory structure:

mkdir -p skill-name/{references,scripts,assets}
touch skill-name/SKILL.md

Alternatively, use the init_skill.py script to generate a template:

scripts/init_skill.py <skill-name> --path <output-directory>

The script creates a skill directory with SKILL.md template and example resource directories.

Step 4: Edit the Skill

When editing the (newly-created or existing) skill, remember that the skill is being created for another instance of OpenHands to use. Focus on including information that would be beneficial and non-obvious to OpenHands. Consider what procedural knowledge, domain-specific details, or reusable assets would help another OpenHands instance execute these tasks more effectively.

Start with Reusable Skill Contents

To begin implementation, start with the reusable resources identified above: scripts/, references/, and assets/ files. Note that this step may require user input. For example, when implementing a brand-guidelines skill, the user may need to provide brand assets or templates to store in assets/, or documentation to store in references/.

Also, delete any example files and directories not needed for the skill. Create only the directories you actually need (references/, scripts/, assets/).

Update SKILL.md

Writing Style: Write the entire skill using imperative/infinitive form (verb-first instructions), not second person. Use objective, instructional language (e.g., "To accomplish X, do Y" rather than "You should do X" or "If you need to do X"). This maintains consistency and clarity for AI consumption.

Description (Frontmatter): Use third-person format with specific trigger phrases:

---
name: skill-name
description: This skill should be used when the user asks to "specific phrase 1", "specific phrase 2", "specific phrase 3". Include exact phrases users would say that should trigger this skill. Be concrete and specific.
---

Good description examples:

description: This skill should be used when the user asks to "create a hook", "add a PreToolUse hook", "validate tool use", "implement prompt-based hooks", or mentions hook events (PreToolUse, PostToolUse, Stop).

Bad description examples:

description: Use this skill when working with hooks.  # Wrong person, vague
description: Load when user needs hook help.  # Not third person
description: Provides hook guidance.  # No trigger phrases

To complete SKILL.md body, answer the following questions:

1. What is the purpose of the skill, in a few sentences?
2. When should the skill be used? (Include this in frontmatter description with specific triggers)
3. In practice, how should OpenHands use the skill? All reusable skill contents developed above should be referenced so that OpenHands knows how to use them.

Keep SKILL.md lean: Target 1,500-2,000 words for the body. Move detailed content to references/:

• Detailed patterns → references/patterns.md
• Advanced techniques → references/advanced.md
• Migration guides → references/migration.md
• API references → references/api-reference.md

Reference resources in SKILL.md:

## Additional Resources

### Reference Files

For detailed patterns and techniques, consult:
- **`references/patterns.md`** - Common patterns
- **`references/advanced.md`** - Advanced use cases

### Example Files

Working examples in `examples/`:
- **`example-script.sh`** - Working example