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pastoon

Auto-convert clipboard JSON to TOON format - 40% fewer LLM tokens. macOS tray + MCP server.

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Use tool

Set up

Runs on your computer. Pick your agent and operating system.

Before you start

  • Node.js 20 or newer
~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "pastoon": {
      "command": "npx",
      "args": [
        "-y",
        "pastoon"
      ]
    }
  }
}

same format Cursor, GitHub Copilot CLI, Junie, JetBrains AI Assistant, Augment (Auggie CLI), Factory Droid, Kiro, Devin CLI +12

Values in angle brackets are placeholders. Restart Claude Desktop after editing its config.Claude Desktop docs

README

synced Oct 23, 2026

pastoon

Auto-convert clipboard JSON to TOON — 40% fewer LLM tokens, zero friction.

What it does

Every time you copy JSON, pastoon silently converts it to TOON format before you paste — saving ~40% of tokens in LLM chat UIs, coding agents, and API calls.

JSON (verbose):                    TOON (40% fewer tokens):
{                                  users[3]{id,name,role}:
  "users": [                         1,Alice,admin
    {"id":1,"name":"Alice",          2,Bob,user
     "role":"admin"},                3,Carol,user
    ...
  ]
}

TOON is lossless — perfect JSON round-trip, same data model, just without the braces, quotes, and repeated keys.

Install

npm install -g pastoon
pastoon setup

That's it. The [P] icon appears in your menu bar. Every JSON you copy is automatically converted.

Supports macOS (LaunchAgent), Linux (systemd user service), and Windows (registry Run key).

Agent integration

pastoon is built with incur — a CLI framework that makes every command available as both a CLI tool and an MCP tool automatically.

Skills (recommended): agents discover and load pastoon commands on-demand, with TOON output natively.

pastoon skills add   # register with your coding agent (Claude Code, OpenCode, etc.)

MCP (fallback): for agents that only support MCP, pastoon also works as an MCP server — no extra code needed, incur provides it automatically.

pastoon mcp add   # register as MCP server with detected coding agents
pastoon --mcp     # start MCP server manually

Available tools (both interfaces):

  • json-to-toon — convert JSON string to TOON (use before reasoning over large JSON)
  • toon-to-json — convert TOON string back to JSON

Or give your agent SETUP.md and say: "Set up pastoon for me."

CLI

pastoon            # JSON → TOON (clipboard)
pastoon --reverse  # TOON → JSON (clipboard)
pastoon --pipe     # stdin → stdout (for scripts)
pastoon --pipe --reverse  # TOON stdin → JSON stdout

pastoon json-to-toon '<json>'   # convert JSON string directly
pastoon toon-to-json '<toon>'   # convert TOON string directly

pastoon setup      # install background service + start tray
pastoon stop       # stop tray
pastoon start      # start tray
pastoon uninstall  # full removal

json-to-toon also accepts --delimiter (, \t |) and --keyFolding (off safe).

What is TOON?

TOON (Token-Oriented Object Notation) is a compact, human-readable format for JSON data. It achieves:

  • ~40% fewer tokens than JSON
  • 76.4% LLM accuracy vs JSON's 75.0%
  • Perfect lossless round-trip
  • Spec-driven with implementations in TypeScript, Python, Go, Rust

License

MIT

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