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Creating Agent Skills

docs/cli/creating-skills.md

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Creating Agent Skills

Agent Skills let you extend Gemini CLI with specialized expertise, procedural workflows, and task-specific resources. This guide walks you through both automated and manual methods for creating and organizing your skills.

Quickstart: Create a skill with a prompt

The fastest way to create a new skill is to use the built-in skill-creator. This meta-skill guides you through designing, scaffolding, and validating your expertise.

Simply ask Gemini CLI to create a skill for you:

"Create a new skill called 'code-reviewer' that analyzes local files for common errors and style violations."

Gemini will then:

  1. Generate a new directory for your skill (for example, my-new-skill/).
  2. Create a SKILL.md file with the necessary YAML frontmatter (name and description).
  3. Create the standard resource directories: scripts/, references/, and assets/.

Once created, you can find your new skill in .gemini/skills/code-reviewer/.

Manual creation

  1. Create a directory for your skill (for example, my-new-skill/).
  2. Create a SKILL.md file inside the new directory.

1. Create the directory structure

The first step is to create the necessary folders for your skill and its scripts.

macOS/Linux

bash
mkdir -p .gemini/skills/code-reviewer/scripts

Windows (PowerShell)

powershell
New-Item -ItemType Directory -Force -Path ".gemini\skills\code-reviewer\scripts"

2. Define the skill (SKILL.md)

The SKILL.md file defines the skill's purpose and instructions for the agent. Create a file at .gemini/skills/code-reviewer/SKILL.md.

markdown
---
name: code-reviewer
description:
  Expertise in reviewing code changes for correctness, security, and style. Use
  when the user asks to "review" their code or a PR.
---

# Code Reviewer Instructions

You act as a senior software engineer specialized in code quality. When this
skill is active, you MUST:

1.  **Analyze**: Review the provided code for logical errors, security
    vulnerabilities, and style violations.
2.  **Review**: Use the bundled `scripts/review.js` utility to perform an
    automated check.
3.  **Feedback**: Provide constructive feedback, clearly distinguishing between
    critical issues and minor improvements.

3. Add the tool logic

Skills can bundle resources like scripts to perform deterministic tasks. Create a file at .gemini/skills/code-reviewer/scripts/review.js.

javascript
// .gemini/skills/code-reviewer/scripts/review.js
const file = process.argv[2];

if (!file) {
  console.error('Usage: node review.js <file>');
  process.exit(1);
}

console.log(`Reviewing ${file}...`);
// Simple mock review logic
setTimeout(() => {
  console.log(`Result: Success (No major issues found in ${file})`);
}, 500);

4. Test the skill

Gemini CLI automatically discovers skills in the .gemini/skills directory.

  1. Start a new session and ask a question that triggers the skill's description: "Can you review index.js"
  2. Gemini identifies the request matches the code-reviewer description and asks for permission to activate it.
  3. Once you approve, Gemini executes the bundled script: node .gemini/skills/code-reviewer/scripts/review.js index.js

To determine whether your skill has been correctly loaded, run the command:

bash
/skills

5. Optional: Share your skill

You can share your skills in several ways depending on your target audience.

  • Workspace skills: Commit your skill to a .gemini/skills/ directory in your project repository.
  • Extensions: Bundle your skill within a Gemini CLI extension.
  • Git repositories: Share the skill directory as a standalone Git repo and install it using gemini skills install <url>.

Core concepts

Now that you've built your first skill, let's explore the core components and workflows for developing more complex expertise.

Skill structure

While a SKILL.md file is the only required component, we recommend the following structure for organizing your skill's resources.

text
my-skill/
├── SKILL.md       (Required) Instructions and metadata
├── scripts/       (Optional) Executable scripts
├── references/    (Optional) Static documentation
└── assets/        (Optional) Templates and other resources

When a skill is activated, the model is granted access to this entire directory. You can instruct the model to use the tools and files found within these folders.

Metadata and triggers

The SKILL.md file uses YAML frontmatter for metadata.

  • name: A unique identifier for the skill. This should match the directory name.
  • description: CRITICAL. This is how Gemini decides when to use the skill. Be specific about the tasks it handles and the keywords that should trigger it.

Discovery tiers

Gemini CLI discovers skills from several locations, following a specific order of precedence (lowest to highest):

  1. Built-in Skills: Included with Gemini CLI (pre-approved).
  2. Extension Skills: Bundled within extensions.
  3. User Skills: ~/.gemini/skills/ or the ~/.agents/skills/ alias.
  4. Workspace Skills: .gemini/skills/ or the .agents/skills/ alias.

Discovery aliases

You can use .agents/skills as an alternative to .gemini/skills. This alias is compatible with other AI agent tools following the Agent Skills standard.

Advanced development

Once you've built a basic skill, you can use specialized scripts and workflows to streamline your development process.

Creation scripts

If you are developing a skill and want to use the same scripts the built-in tools use, you can find them in the core package. These scripts help automate the initialization, validation, and packaging of skills.

  • Initialize: node scripts/init_skill.cjs <name> --path <dir>
  • Validate: node scripts/validate_skill.cjs <path/to/skill>
  • Package: node scripts/package_skill.cjs <path/to/skill> (Creates a .skill zip file)

Linking for local development

If you are developing a skill in a separate directory, you can link it to your user skills directory for testing:

bash
gemini skills link .

Next steps