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

# Skill

> Extend agent capabilities with markdown instruction sets

Skills are markdown-based instruction sets that extend agent capabilities without writing new tool code. Each skill is a directory containing a `SKILL.md` file with frontmatter metadata and detailed instructions.

Unlike tools, skills are not callable directly. The agent uses the auto-registered `Skill` viewer tool to read a skill's instructions, then follows those instructions using its existing tools.

## Register Skill

Pass skill sources to the `Toolkit` constructor through `skills_or_loaders`. Each entry can be a directory path string, a `Skill` object, or a `SkillLoaderBase` subclass:

<CodeGroup>
  ```python Directory path (simple) theme={null}
  from agentscope.tool import Toolkit

  toolkit = Toolkit(
      skills_or_loaders=["/path/to/skills"],
  )
  ```

  ```python LocalSkillLoader (with subdirectory scanning) theme={null}
  from agentscope.tool import Toolkit
  from agentscope.skill import LocalSkillLoader

  loader = LocalSkillLoader(
      directory="/path/to/skills",
      scan_subdir=True,
  )

  toolkit = Toolkit(skills_or_loaders=[loader])
  ```
</CodeGroup>

## How Skill Works

When a `Toolkit` is constructed with skills, the registration and lookup flow runs in two phases.

At initialization:

* The toolkit scans every registered skill source and collects each skill's name, description, and directory.
* It auto-registers the built-in `Skill` viewer tool.
* It composes a system-prompt fragment listing the available skills (name and description only) and instructing the agent to invoke the `Skill` viewer to read the full content.

At runtime:

* The agent picks a skill by name and calls the `Skill` viewer.
* The viewer reads the corresponding `SKILL.md` and returns its full markdown.
* The agent follows those instructions using its already-equipped tools.

<Note>
  Skills are not tools: the agent cannot call a skill directly. It must first use the `Skill` viewer to read the instructions, then execute the steps described within using its other tools.
</Note>