Tooner — Data skill for Claude Code

Tooner - Claude Code Hook

**Reduce LLM token usage by up to 60% with automatic JSON compression**

Tooner is a Claude Code hook that automatically compresses structured JSON data into the efficient [Toon format](https://github.com/toon-format/toon) before sending to LLMs. Uses the official [toon-python library](https://github.com/toon-format/toon-python) for compression. Perfect for working with large datasets, API responses, and tabular data.

---

**📚 Quick Navigation:** [Installation](#-installation) · [Testing](#-testing-with-mcp-server-optional) · [How It Works](#-how-it-works) · [Development](#-development) · [Contributing](#-contributing)

---

⚡ Get Started

**Install the hook:** Follow the [installation steps](#-installation) to automatically compress JSON data in Claude Code.

**Want to test the compression first?** [Use the MCP test server](#-testing-with-mcp-server-optional) with Claude Desktop to explore how Toon compression works.

---

🚀 Quick Overview

**What it does:** Converts verbose JSON arrays into compact Toon format, dramatically reducing tokens.

**Example:**

// Before (100 tokens)
[
  {"id": 1, "name": "Alice", "role": "admin", "status": "active"},
  {"id": 2, "name": "Bob", "role": "user", "status": "active"},
  {"id": 3, "name": "Carol", "role": "admin", "status": "inactive"}
]

// After (55 tokens) - 45% savings!
data[3]{id,name,role,status}:
 1,Alice,admin,active
 2,Bob,user,active
 3,Carol,admin,inactive

📦 Installation

Requirements

• Python 3.10+ (required for toon-python library)
• pip (Python package manager)
• Claude Code CLI

**Note:**

• The installer automatically handles externally-managed Python environments using pip --user
• If you have Python < 3.10, the installer will warn you and skip compression (hook still installs but won't compress)

Automatic Installation (Recommended)

Run this one command to install everything:

curl -fsSL https://raw.githubusercontent.com/mostafamoq