Show HN: Mcptoon – Token-efficient MCP CLI client

mcptoon MCP tool discovery costs 10,000+ tokens. mcptoon costs 350. One MCP client for every AI agent. Cross-platform. Zero dependencies. If this saves you tokens, please star the repo — it helps others discover it. English | 中文文档 | Report Bug | Request Feature

The problem

Every MCP-enabled conversation burns tokens on syntax, not data:

Your agent connects to 5 MCP servers. Listing their tools: ~10,000 tokens of JSON.

of JSON. Your agent calls 20 tools. Each returns 500-3,000 tokens wrapped in {"content":[{"type":"text","text":"..."}]} .

. Total MCP overhead: 40,000-70,000 tokens before any actual thinking happens.

On a 128K context window, that's 30-55% gone. Not on work. On syntax.

The solution

mcptoon is a CLI client that connects to any MCP server (stdio or HTTP) and outputs TOON (Token-Optimized Object Notation) instead of JSON.

Operation JSON tokens mcptoon tokens Savings Tool discovery (96 tools) ~2,000 ~60 97% Tool result (structured data) ~800 ~350 56% Tool result (raw HTML/text) ~1,000 ~900 10%

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