How to Invoke a HumanLayer Skill: A Complete Guide to Using the NPX Skills CLI

Invoke a HumanLayer skill by installing it with npx skills add humanlayer/skills --skill <name> and then running it as a slash command like /show-me.

HumanLayer skills are self-contained CLI plugins that extend your development workflow with specialized capabilities. Each skill exposes both a command-line interface through the npx skills helper and a runtime slash command. This guide covers the complete workflow for discovering, installing, and invoking skills from the humanlayer/skills repository.

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Adding a HumanLayer Skill to Your Project

The first step to invoke any HumanLayer skill is local installation. The skills CLI pulls the skill definition directly from the repository and registers it for your project.

Run this command once per repository:

npx skills add humanlayer/skills --skill <SKILL_NAME>

The CLI fetches the skill's SKILL.md and metadata from the repository's plugins/<skill> directory. For example, to install the show-me skill:

npx skills add humanlayer/skills --skill show-me

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Invoking an Installed Skill

After installation, invoke a HumanLayer skill using its root path as a slash command. The pattern is consistent across all skills:

/<skill-root-path>

The README.md in humanlayer/skills documents this pattern with the generic example: /show-me at lines 77-81.

Practical Examples

# Install and invoke the design-control-loop skill

npx skills add humanlayer/skills --skill design-control-loop
/design-control-loop

# Install and invoke the narrow-react-prop-types skill

npx skills add humanlayer/skills --skill narrow-react-prop-types
/narrow-react-prop-types

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How Skill Invocation Works Under the Hood

The skills CLI follows a predictable pipeline when you invoke a HumanLayer skill:

1. Reads plugin.json — Located at plugins/<skill>/.claude-plugin/plugin.json, this file contains metadata including the source path pointing to the skill's folder (e.g., ./plugins/show-me).

2. Bundles skill assets — The CLI collects the SKILL.md file (the declarative skill description) plus any reference files like response-template.md or memory-template.md.

3. Executes via Claude Code backend — When you run the slash command, the CLI transmits the request to the Claude Code backend, which parses SKILL.md and executes the defined skill logic.

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Finding Available HumanLayer Skills

The repository's Marketplace manifest at .claude-plugin/marketplace.json contains the canonical list of all built-in skills. Each entry specifies the skill name, description, and source directory:

"plugins": [
  {
    "name": "show-me",
    "description": "Explain the current topic with concise diagrams, code-shape sketches, and focused HTML artifacts",
    "source": "./plugins/show-me"
  }
]

Browse this file to discover which HumanLayer skills you can invoke in your projects.

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The show-me Skill: A Complete Example

The show-me skill demonstrates the full invocation pattern. Its definition lives at plugins/show-me/skills/show-me/SKILL.md and specifies visual output formats including pseudocode, call trees, Mermaid diagrams, and diff snippets.

To invoke this HumanLayer skill:

# One-time installation

npx skills add humanlayer/skills --skill show-me

# Run the skill

/show-me

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Key Files for Understanding Skill Invocation

File	Purpose
README.md	General usage instructions and the "Then invoke" example
.claude-plugin/marketplace.json	Master list of all shipped skills with descriptions and source paths
plugins/<skill>/skills/<skill>/SKILL.md	Declarative description defining skill behavior
plugins/<skill>/.claude-plugin/plugin.json	CLI metadata for locating skill sources

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Summary

• HumanLayer skills are installed via npx skills add humanlayer/skills --skill <name> and invoked as /<skill> slash commands.
• The skills CLI reads plugin.json metadata and bundles SKILL.md with reference files before execution.
• Available skills are cataloged in .claude-plugin/marketplace.json with full descriptions and source paths.
• Installation is per-repository; invocation is repeatable and consistent across all skills.

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Frequently Asked Questions

What is the exact command to invoke a HumanLayer skill after installation?

Run the skill's root path as a slash command: /<skill-name>. For example, after installing the show-me skill, type /show-me in your terminal.

Where does the skills CLI find skill definitions?

The CLI retrieves metadata from plugins/<skill>/.claude-plugin/plugin.json and the skill description from plugins/<skill>/skills/<skill>/SKILL.md within the humanlayer/skills repository.

Can I invoke a HumanLayer skill without installing it first?

No. You must run npx skills add humanlayer/skills --skill <name> once per repository to register the skill locally before any slash command invocation will work.

How do I discover which HumanLayer skills are available?

Examine .claude-plugin/marketplace.json in the repository root. This JSON file lists every built-in skill with its name, description, and source directory path.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
    }
  }
}