---
title: "Agent Skills in the SDK"
source: "https://code.claude.com/docs/en/agent-sdk/skills"
author:
published:
created: 2026-04-17
description: "Extend Claude with specialized capabilities using Agent Skills in the Claude Agent SDK"
tags:
  - "clippings"
---
## Overview

Agent Skills extend Claude with specialized capabilities that Claude autonomously invokes when relevant. Skills are packaged as `SKILL.md` files containing instructions, descriptions, and optional supporting resources.

For comprehensive information about Skills, including benefits, architecture, and authoring guidelines, see the [Agent Skills overview](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/overview).

## How Skills Work with the SDK

When using the Claude Agent SDK, Skills are:

1. **Defined as filesystem artifacts**: Created as `SKILL.md` files in specific directories (`.claude/skills/`)
2. **Loaded from filesystem**: Skills are loaded from filesystem locations governed by `settingSources` (TypeScript) or `setting_sources` (Python)
3. **Automatically discovered**: Once filesystem settings are loaded, Skill metadata is discovered at startup from user and project directories; full content loaded when triggered
4. **Model-invoked**: Claude autonomously chooses when to use them based on context
5. **Enabled via allowed\_tools**: Add `"Skill"` to your `allowed_tools` to enable Skills

Unlike subagents (which can be defined programmatically), Skills must be created as filesystem artifacts. The SDK does not provide a programmatic API for registering Skills.

Skills are discovered through the filesystem setting sources. With default `query()` options, the SDK loads user and project sources, so skills in `~/.claude/skills/` and `<cwd>/.claude/skills/` are available. If you set `settingSources` explicitly, include `'user'` or `'project'` to keep skill discovery, or use the [`plugins` option](https://code.claude.com/docs/en/agent-sdk/plugins) to load skills from a specific path.

## Using Skills with the SDK

To use Skills with the SDK, you need to:

1. Include `"Skill"` in your `allowed_tools` configuration
2. Configure `settingSources` / `setting_sources` to load Skills from the filesystem

Once configured, Claude automatically discovers Skills from the specified directories and invokes them when relevant to the user’s request.

```python
import asyncio
from claude_agent_sdk import query, ClaudeAgentOptions

async def main():
    options = ClaudeAgentOptions(
        cwd="/path/to/project",  # Project with .claude/skills/
        setting_sources=["user", "project"],  # Load Skills from filesystem
        allowed_tools=["Skill", "Read", "Write", "Bash"],  # Enable Skill tool
    )

    async for message in query(
        prompt="Help me process this PDF document", options=options
    ):
        print(message)

asyncio.run(main())
```

## Skill Locations

Skills are loaded from filesystem directories based on your `settingSources` / `setting_sources` configuration:

- **Project Skills** (`.claude/skills/`): Shared with your team via git - loaded when `setting_sources` includes `"project"`
- **User Skills** (`~/.claude/skills/`): Personal Skills across all projects - loaded when `setting_sources` includes `"user"`
- **Plugin Skills**: Bundled with installed Claude Code plugins

## Creating Skills

Skills are defined as directories containing a `SKILL.md` file with YAML frontmatter and Markdown content. The `description` field determines when Claude invokes your Skill.

**Example directory structure**:

```shellscript
.claude/skills/processing-pdfs/
└── SKILL.md
```

For complete guidance on creating Skills, including SKILL.md structure, multi-file Skills, and examples, see:

- [Agent Skills in Claude Code](https://code.claude.com/docs/en/skills): Complete guide with examples
- [Agent Skills Best Practices](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices): Authoring guidelines and naming conventions

## Tool Restrictions

The `allowed-tools` frontmatter field in SKILL.md is only supported when using Claude Code CLI directly. **It does not apply when using Skills through the SDK**.

When using the SDK, control tool access through the main `allowedTools` option in your query configuration.

To control tool access for Skills in SDK applications, use `allowedTools` to pre-approve specific tools. Without a `canUseTool` callback, anything not in the list is denied:

Import statements from the first example are assumed in the following code snippets.

```python
options = ClaudeAgentOptions(
    setting_sources=["user", "project"],  # Load Skills from filesystem
    allowed_tools=["Skill", "Read", "Grep", "Glob"],
)

async for message in query(prompt="Analyze the codebase structure", options=options):
    print(message)
```

## Discovering Available Skills

To see which Skills are available in your SDK application, simply ask Claude:

```python
options = ClaudeAgentOptions(
    setting_sources=["user", "project"],  # Load Skills from filesystem
    allowed_tools=["Skill"],
)

async for message in query(prompt="What Skills are available?", options=options):
    print(message)
```

Claude will list the available Skills based on your current working directory and installed plugins.

## Testing Skills

Test Skills by asking questions that match their descriptions:

```python
options = ClaudeAgentOptions(
    cwd="/path/to/project",
    setting_sources=["user", "project"],  # Load Skills from filesystem
    allowed_tools=["Skill", "Read", "Bash"],
)

async for message in query(prompt="Extract text from invoice.pdf", options=options):
    print(message)
```

Claude automatically invokes the relevant Skill if the description matches your request.

## Troubleshooting

### Skills Not Found

**Check settingSources configuration**: Skills are discovered through the `user` and `project` setting sources. If you set `settingSources` / `setting_sources` explicitly and omit those sources, skills are not loaded:

```python
# Skills not loaded: setting_sources excludes user and project
options = ClaudeAgentOptions(setting_sources=[], allowed_tools=["Skill"])

# Skills loaded: user and project sources included
options = ClaudeAgentOptions(
    setting_sources=["user", "project"],
    allowed_tools=["Skill"],
)
```

For more details on `settingSources` / `setting_sources`, see the [TypeScript SDK reference](https://code.claude.com/docs/en/agent-sdk/typescript#setting-source) or [Python SDK reference](https://code.claude.com/docs/en/agent-sdk/python#setting-source).

**Check working directory**: The SDK loads Skills relative to the `cwd` option. Ensure it points to a directory containing `.claude/skills/`:

```python
# Ensure your cwd points to the directory containing .claude/skills/
options = ClaudeAgentOptions(
    cwd="/path/to/project",  # Must contain .claude/skills/
    setting_sources=["user", "project"],  # Loads skills from these sources
    allowed_tools=["Skill"],
)
```

See the “Using Skills with the SDK” section above for the complete pattern.

**Verify filesystem location**:

```shellscript
# Check project Skills
ls .claude/skills/*/SKILL.md

# Check personal Skills
ls ~/.claude/skills/*/SKILL.md
```

### Skill Not Being Used

**Check the Skill tool is enabled**: Confirm `"Skill"` is in your `allowedTools`.

**Check the description**: Ensure it’s specific and includes relevant keywords. See [Agent Skills Best Practices](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices#writing-effective-descriptions) for guidance on writing effective descriptions.

### Additional Troubleshooting

For general Skills troubleshooting (YAML syntax, debugging, etc.), see the [Claude Code Skills troubleshooting section](https://code.claude.com/docs/en/skills#troubleshooting).

## Related Documentation

### Skills Guides

- [Agent Skills in Claude Code](https://code.claude.com/docs/en/skills): Complete Skills guide with creation, examples, and troubleshooting
- [Agent Skills Overview](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/overview): Conceptual overview, benefits, and architecture
- [Agent Skills Best Practices](https://platform.claude.com/docs/en/agents-and-tools/agent-skills/best-practices): Authoring guidelines for effective Skills
- [Agent Skills Cookbook](https://platform.claude.com/cookbook/skills-notebooks-01-skills-introduction): Example Skills and templates

### SDK Resources

- [Subagents in the SDK](https://code.claude.com/docs/en/agent-sdk/subagents): Similar filesystem-based agents with programmatic options
- [Slash Commands in the SDK](https://code.claude.com/docs/en/agent-sdk/slash-commands): User-invoked commands
- [SDK Overview](https://code.claude.com/docs/en/agent-sdk/overview): General SDK concepts
- [TypeScript SDK Reference](https://code.claude.com/docs/en/agent-sdk/typescript): Complete API documentation
- [Python SDK Reference](https://code.claude.com/docs/en/agent-sdk/python): Complete API documentation