add-skill

A command for adding a new skill to a Claude Code plugin. A skill is a reusable set of instructions that guides the coding agent during a particular kind of work.

In plain words
What is it for?
Use it to create a skill folder and its SKILL.md file, optionally with supporting directories. It can add the skill to the current plugin or to a named plugin in a marketplace.
Why use it?
It avoids manually creating the folders and files a skill needs. It also checks that the command is being run in a valid plugin or plugin collection.

Command

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add commands/ivan-magda/claude-code-plugin-template/add-skill
Clone the repo
git clone --depth 1 https://github.com/ivan-magda/claude-code-plugin-template
Per session 11 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 2,959 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00011 $0.02959
Opus 5 $0.00005 $0.01479
Sonnet 5 $0.00002 $0.00592
Haiku 4.5 $0.00001 $0.00296

Measured 2d ago against content hash a23760e5bdf8, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

add-skill scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

2 near-identical copies found in the catalogue:

plugins/plugin-development/commands/add-skill.md · 392 lines

How it starts

The opening of the file, as written. The whole thing — 392 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Add Skill

Create a new Skill folder with SKILL.md and supporting directories.

Arguments

  • $1 (required): Skill name in kebab-case (e.g., code-review)
  • $2 (optional): Description of when to use this Skill in quotes (e.g., "Use when reviewing code or PRs")
  • --plugin=<plugin-name> (optional): Specify which plugin to add the skill to

Usage:

# From within a plugin directory, with description
/plugin-development:add-skill code-review "Use when reviewing code or analyzing pull requests"

# Without description (uses default)
/plugin-development:add-skill code-review

# From marketplace root, specifying plugin
/plugin-development:add-skill code-review "Use when reviewing code" --plugin=plugin-development

Prerequisites

  • Must be run from either:
    • A plugin root directory (containing .claude-plugin/plugin.json), OR
    • A marketplace root directory (containing .claude-plugin/marketplace.json)
  • skills/ directory will be created if needed

Instructions

Validation

IMPORTANT: When running test commands for validation (checking directories, files, etc.), use require_user_approval: false since these are read-only checks.

  1. Detect context and target plugin (output thoughts during this process):

    a. Check if we're in a plugin directory:

    • Look for .claude-plugin/plugin.json in current directory
    • Output: "Checking for plugin directory..."
    • If found:
      • Output: "Found plugin.json - using current directory as target plugin"
      • Use current directory as target plugin
    • If not found:
      • Output: "Not in a plugin directory, checking for marketplace..."

    b. If not in plugin directory, check if we're in marketplace root:

    • Look for .claude-plugin/marketplace.json in current directory
    • If found:
      • Output: "Found marketplace.json - this is a marketplace root"
      • This is a marketplace root
    • If not found:
      • Output: "Error: Neither plugin.json nor marketplace.json found"
      • Show error and exit

Read the full file on GitHub · 392 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 2d ago First seen · 392 lines · 0 tokens per session scan A a23760e5bdf8

Subscribe to this mod's changes

add-skill is a command published in the GitHub repository ivan-magda/claude-code-plugin-template (68 stars, last pushed 2mo ago), licensed MIT. It adds 11 tokens to every session and 2,959 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.