What it does

json2toon.co runs a remote Model Context Protocol (MCP) server. Once you connect it, your AI assistant can convert data to TOON, a format that uses about 40% fewer tokens than JSON, and decode it back. It is useful when you are preparing prompts, fixtures or RAG context and want the compact version without leaving the chat.

Endpoint (Streamable HTTP, no authentication):

https://json2toon.co/api/mcp

Tools

json_to_toon: converts a JSON document to TOON. Optional delimiter: comma (default), tab or pipe.
toon_to_json: decodes TOON back to pretty-printed JSON.

For example, ask “convert this JSON to TOON” with:

{"users":[{"id":1,"name":"Ann","role":"admin"},{"id":2,"name":"Bob","role":"user"}]}

and the tool returns:

users[2]{id,name,role}:
  1,Ann,admin
  2,Bob,user

Each result also includes a link that opens the same data in the online converter, where you can compare token counts across formats.

Setup

ChatGPT

Settings → Apps → Advanced settings → turn on Developer mode. Then create an app, paste the URL below and choose no authentication.

https://json2toon.co/api/mcp

Claude (claude.ai and desktop)

Settings → Connectors → Add custom connector, and paste the URL.

https://json2toon.co/api/mcp

Claude Code

Run this in your terminal:

claude mcp add --transport http json2toon https://json2toon.co/api/mcp

Codex CLI

Add this to ~/.codex/config.toml:

[mcp_servers.json2toon]
url = "https://json2toon.co/api/mcp"

Cursor

Add this to ~/.cursor/mcp.json (or .cursor/mcp.json in your project):

{
  "mcpServers": {
    "json2toon": { "url": "https://json2toon.co/api/mcp" }
  }
}

VS Code

Add this to .vscode/mcp.json:

{
  "servers": {
    "json2toon": { "type": "http", "url": "https://json2toon.co/api/mcp" }
  }
}

Menu names in ChatGPT and Claude change from time to time. If a step does not match what you see, look for “connectors”, “apps” or “MCP” in the settings.

Limits and privacy

Unlike the web converter, which runs in your browser, MCP conversions run on our server, because that is how remote MCP works. Input is converted in memory and is not stored. Requests are rate-limited per IP address. For bulk or automated conversion, use the conversion API or the TOON library directly. See the privacy policy for details.

TOON MCP Server