add-skill

An instruction set that imports another coding skill from a GitHub repository into the current workspace. GitHub is a website for hosting and sharing code.

In plain words
What is it for?
For adding a skill when the user provides a GitHub repository or skill URL.
Why use it?
It avoids manually copying files and checking whether the imported skill was installed correctly.

Skill for Claude CodeCodex

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 skills/openhands/extensions/add-skill
Any agent
npx skills add OpenHands/extensions --skill add-skill
Clone the repo
git clone --depth 1 https://github.com/OpenHands/extensions

Made for: Claude Code, Codex.

Per session 119 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 505 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 $0.00119 $0.00505
Opus 5 $0.00060 $0.00253
Sonnet 5 $0.00024 $0.00101
Haiku 4.5 $0.00012 $0.00051

Measured 2d ago against content hash 3d7f1557d8ff, 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.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/fetch_skill.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

skills/add-skill/SKILL.md · 50 lines

What it actually says

Add Skill

Import skills from GitHub repositories into the current workspace.

Workflow

When a user requests to add a skill from a GitHub URL:

  1. Parse the URL to extract repository owner, name, and skill path
  2. Fetch the skill using the bundled script:
    python3 <this-skill-path>/scripts/fetch_skill.py "<github-url>" "<workspace-path>"
    
  3. Verify that SKILL.md exists in the destination
  4. Inform the user the skill is now available

URL Formats Supported

  • https://github.com/owner/repo/tree/main/path/to/skill
  • https://github.com/owner/repo/skill-name
  • github.com/owner/repo/skill-name
  • owner/repo/skill-name (shorthand)

Example

User: /add-skill https://github.com/OpenHands/extensions/tree/main/skills/codereview

# Run the fetch script
python3 scripts/fetch_skill.py "https://github.com/OpenHands/extensions/tree/main/skills/codereview" "/path/to/workspace"

# Verify installation
ls /path/to/workspace/.agents/skills/codereview/SKILL.md

On Windows, use python if python3 is not available and verify with PowerShell, for example: Test-Path C:\path\to\workspace\.agents\skills\codereview\SKILL.md.

Response: "✅ Added codereview to your workspace. The skill is now available."

Notes

  • Creates .agents/skills/ directory if it doesn't exist
  • Uses GITHUB_TOKEN for authentication (required for private repos)
  • Warns before overwriting existing skills with the same name
Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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 · 50 lines · 119 tokens per session scan A 3d7f1557d8ff

Subscribe to this mod's changes

add-skill is a skill published in the GitHub repository OpenHands/extensions (137 stars, last pushed 4d ago), licensed MIT. It adds 119 tokens to every session and 505 once invoked, about $0.0006 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.

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