> ## Documentation Index
> Fetch the complete documentation index at: https://code.claude.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Agent Skills in the SDK

> Extend Claude with specialized capabilities using Agent Skills in the Claude Agent SDK

## 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. **Filtered via the `skills` option**: Discovered skills are enabled by default. Pass a list of skill names, `"all"`, or `[]` to control which are available in the session

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.

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

## Using Skills with the SDK

Set the `skills` option on `query()` to control which Skills are available to the session. When omitted, discovered Skills are enabled and the Skill tool is available, matching CLI behavior. Pass `"all"` to enable every discovered Skill, a list of Skill names to enable only those, or `[]` to disable all. When you set `skills`, the SDK enables the Skill tool automatically, so you do not need to list it in `allowedTools`.

Once configured, Claude automatically discovers Skills from the filesystem and invokes them when relevant to the user's request.

<CodeGroup>
  ```python Python theme={null}
  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
          skills="all",  # Enable every discovered Skill
          allowed_tools=["Read", "Write", "Bash"],
      )

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


  asyncio.run(main())
  ```

  ```typescript TypeScript theme={null}
  import { query } from "@anthropic-ai/claude-agent-sdk";

  for await (const message of query({
    prompt: "Help me process this PDF document",
    options: {
      cwd: "/path/to/project", // Project with .claude/skills/
      settingSources: ["user", "project"], // Load Skills from filesystem
      skills: "all", // Enable every discovered Skill
      allowedTools: ["Read", "Write", "Bash"]
    }
  })) {
    console.log(message);
  }
  ```
</CodeGroup>

To enable only specific Skills, pass their names. Names match the `name` field in `SKILL.md` or the Skill's directory name. Use `plugin:skill` for plugin-provided Skills.

<CodeGroup>
  ```python Python theme={null}
  options = ClaudeAgentOptions(skills=["pdf", "docx"])
  ```

  ```typescript TypeScript theme={null}
  const options = { skills: ["pdf", "docx"] };
  ```
</CodeGroup>

The `skills` option is a context filter, not a sandbox. Unlisted Skills are hidden from the model and rejected by the Skill tool, but their files remain on disk and are reachable through Read and Bash.

## 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**:

```bash theme={null}
.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](/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

<Note>
  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.
</Note>

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:

<Note>
  Import statements from the first example are assumed in the following code snippets.
</Note>

<CodeGroup>
  ```python Python theme={null}
  options = ClaudeAgentOptions(
      setting_sources=["user", "project"],  # Load Skills from filesystem
      skills="all",
      allowed_tools=["Read", "Grep", "Glob"],
  )

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

  ```typescript TypeScript theme={null}
  for await (const message of query({
    prompt: "Analyze the codebase structure",
    options: {
      settingSources: ["user", "project"], // Load Skills from filesystem
      skills: "all",
      allowedTools: ["Read", "Grep", "Glob"],
      permissionMode: "dontAsk" // Deny anything not in allowedTools
    }
  })) {
    console.log(message);
  }
  ```
</CodeGroup>

## Discovering Available Skills

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

<CodeGroup>
  ```python Python theme={null}
  options = ClaudeAgentOptions(
      setting_sources=["user", "project"],  # Load Skills from filesystem
      skills="all",
  )

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

  ```typescript TypeScript theme={null}
  for await (const message of query({
    prompt: "What Skills are available?",
    options: {
      settingSources: ["user", "project"], // Load Skills from filesystem
      skills: "all"
    }
  })) {
    console.log(message);
  }
  ```
</CodeGroup>

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:

<CodeGroup>
  ```python Python theme={null}
  options = ClaudeAgentOptions(
      cwd="/path/to/project",
      setting_sources=["user", "project"],  # Load Skills from filesystem
      skills="all",
      allowed_tools=["Read", "Bash"],
  )

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

  ```typescript TypeScript theme={null}
  for await (const message of query({
    prompt: "Extract text from invoice.pdf",
    options: {
      cwd: "/path/to/project",
      settingSources: ["user", "project"], // Load Skills from filesystem
      skills: "all",
      allowedTools: ["Read", "Bash"]
    }
  })) {
    console.log(message);
  }
  ```
</CodeGroup>

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:

<CodeGroup>
  ```python Python theme={null}
  # Skills not loaded: setting_sources excludes user and project
  options = ClaudeAgentOptions(setting_sources=[], skills="all")

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

  ```typescript TypeScript theme={null}
  // Skills not loaded: settingSources excludes user and project
  const options = {
    settingSources: [],
    skills: "all"
  };

  // Skills loaded: user and project sources included
  const options = {
    settingSources: ["user", "project"],
    skills: "all"
  };
  ```
</CodeGroup>

For more details on `settingSources`/`setting_sources`, see the [TypeScript SDK reference](/en/agent-sdk/typescript#settingsource) or [Python SDK reference](/en/agent-sdk/python#settingsource).

**Check working directory**: The SDK loads Skills from `.claude/skills/` in the `cwd` option and in every parent directory up to the repository root. Ensure `cwd` points at or below the directory containing `.claude/skills/`, within the same repository:

<CodeGroup>
  ```python Python theme={null}
  # Ensure your cwd points to the directory containing .claude/skills/
  options = ClaudeAgentOptions(
      cwd="/path/to/project",  # .claude/skills/ here or in a parent directory
      setting_sources=["user", "project"],  # Loads skills from these sources
      skills="all",
  )
  ```

  ```typescript TypeScript theme={null}
  // Ensure your cwd points to the directory containing .claude/skills/
  const options = {
    cwd: "/path/to/project", // .claude/skills/ here or in a parent directory
    settingSources: ["user", "project"], // Loads skills from these sources
    skills: "all"
  };
  ```
</CodeGroup>

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

**Verify filesystem location**:

```bash theme={null}
# Check project Skills
ls .claude/skills/*/SKILL.md

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

### Skill Not Being Used

**Check the `skills` option**: If you passed a `skills` list, confirm the skill's name is included. Passing `[]` disables all skills.

**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](/en/skills#troubleshooting).

## Related Documentation

### Skills Guides

* [Agent Skills in Claude Code](/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](/en/agent-sdk/subagents): Similar filesystem-based agents with programmatic options
* [Slash Commands in the SDK](/en/agent-sdk/slash-commands): User-invoked commands
* [SDK Overview](/en/agent-sdk/overview): General SDK concepts
* [TypeScript SDK Reference](/en/agent-sdk/typescript): Complete API documentation
* [Python SDK Reference](/en/agent-sdk/python): Complete API documentation