Zero Dependencies, 250KB, 486 Tests: What I Learned Building an MCP Client
This is not a product pitch. It's an engineering diary. If you want the pitch, the README is here. This is about the cost of zero.
The setup
Six weeks ago I started building mcptoon — a CLI tool that sits between AI agents (Claude Code, Cursor, Codex) and MCP servers. The problem it solves: MCP tool schemas get injected into your context window as JSON. 255 tools = ~91K tokens of JSON braces, brackets, quotes, and commas — before any actual work happens.
mcptoon keeps schemas out of context. The agent runs shell commands. Only the compact result enters context.
