<!--
name: 'Tool Description: Skill'
description: Default SDK built-in tool description and input schema for Skill.
sdkPackage: '@anthropic-ai/claude-agent-sdk@0.3.168'
claudeCodeVersion: '2.1.168'
tool: "Skill"
-->
# Tool Description: Skill

## Metadata

- Request location: `tools[]`
- Tool name: `Skill`
- Input schema properties: `skill`, `args`

## Description

Execute a skill within the main conversation

When users ask you to perform tasks, check if any of the available skills match. Skills provide specialized capabilities and domain knowledge.

When users reference a "slash command" or "/<something>", they are referring to a skill. Use this tool to invoke it.

How to invoke:
- Set `skill` to the exact name of an available skill (no leading slash). For plugin-namespaced skills use the fully qualified `plugin:skill` form.
- Set `args` to pass optional arguments.

Important:
- Available skills are listed in system-reminder messages in the conversation
- Only invoke a skill that appears in that list, or one the user explicitly typed as `/<name>` in their message. Never guess or invent a skill name from training data; otherwise do not call this tool
- When a skill matches the user's request, this is a BLOCKING REQUIREMENT: invoke the relevant Skill tool BEFORE generating any other response about the task
- NEVER mention a skill without actually calling this tool
- Do not invoke a skill that is already running
- Do not use this tool for built-in CLI commands (like /help, /clear, etc.)
- If you see a <command-name> tag in the current conversation turn, the skill has ALREADY been loaded - follow the instructions directly instead of calling this tool again


## Input Schema

```json
{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "type": "object",
  "properties": {
    "skill": {
      "description": "The name of a skill from the available-skills list. Do not guess names.",
      "type": "string"
    },
    "args": {
      "description": "Optional arguments for the skill",
      "type": "string"
    }
  },
  "required": [
    "skill"
  ],
  "additionalProperties": false
}
```

## Token Impact

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- Complete definition estimated tokens: **604**
- Measurement: captured tool object serialized independently as JSON text against the common baseline
- Additivity: independent, non-additive estimate
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