Cut MCP Token Waste 99%: The 50KB CLI That Keeps Schemas Out of Context

MCP Token Bloat: The Silent Context Killer

If you've added more than a few MCP servers to Claude Code, you've felt it: the context window fills with JSON schemas before you even start. The MCP community itself says "MCP is unusable past 5 servers," and Latent Space's analysis confirms a "scaling cliff around 20-30 tools."

Why? Every MCP server you connect pushes its tool definitions into your agent's context as verbose JSON. Browser tools like puppeteer or playwright alone can add 50,000-100,000+ tokens of {"type":"object","properties":...} noise. That's context you're paying for but never using.

The Fix: mcptoon CLI

mcptoon (GitHub: activeing123/mcptoon) is a 50KB Python CLI that flips the model: instead of Claude Code connecting to MCP servers as a client, your agent runs mcptoon commands directly. Schemas live on disk in ~/.mcptoon/config.json—they never enter context. Only the compact output you request does.

Measured Results (255 tools, 5 formats)

With 255 tools, JSON costs 90,804 tokens. mcptoon's compact mode: 117 tokens. That's a 99.87% reduction—freeing your context for actual work.

TOON vs JSON

JSON (287 tokens for one tool):

[{"name":"search_web","description":"Search the web","inputSchema":{"type":"object","properties":{"query":{"type":"string"},"num_results":{"type":"number","default":5}},"required":["query"]}}]

TOON (5 tokens):

search_web fetch_url

Simon Willison nailed it: "JSON is the least token-efficient format possible for structured data sent to an LLM." TOON strips away everything but the essentials.

Setup: 3 Commands

pip install mcptoon
mcptoon init
mcptoon add fetch --stdio npx -y @modelcontextprotocol/server-fetch
mcptoon manifest --compact  # → all tool names, 117 tokens

Your agent can even install its own tools:

mcptoon add github --stdio npx -y @modelcontextprotocol/server-github

Works with Claude Code, Cursor, Codex, OpenCode, CatPaw—any agent that runs shell commands. Zero dependencies, Apache 2.0.

Why This Matters for Claude Code Users

• Context death solved: Keep 10+ servers without eating your window.
• Config hell gone: No more hand-editing claude_desktop_config.json—one config file, all tools.
• Agent self-service: Your agent can add tools on the fly via mcptoon add.
• Reconfigure once: Same config works across all agents—no per-agent redo.
• Stop paying for JSON garbage: Every MCP result in JSON wastes ~80 tokens for 6 tokens of data. Over 200 tool calls, that's 15,000 tokens of syntax waste.

Try It Now

1. Install: pip install mcptoon
2. Init: mcptoon init
3. Add your most-used servers (fetch, github, etc.)
4. Ask Claude Code to run mcptoon manifest --compact and see the token savings instantly.

Your context window is precious. Stop letting MCP schemas eat it alive.

Source: dev.to