RTK, Model Routing, and the Community Tools That Actually Work With Claude Code

This is Part 2 of a series on getting more out of Claude Code. Part 1 covered the 50,000 token overhead problem, the 44% reduction fix, and the memory/lessons.md system. In Part 1, I mentioned RTK saved me 60-90% on tool output tokens. This post goes deeper: how RTK actually works under the hood, the difference between Unix and Windows installations, model routing for subagents, environment variables for cost control, and 7 community tools I tested (most of which I didn't end up using). RTK: How It Actually Works RTK (Rust Token Killer) is a Rust-based CLI proxy that intercepts shell commands, runs them, and compresses the output before it reaches your AI tool's context window. It supports 10+ AI coding tools including Claude Code, GitHub Copilot, Cursor, Gemini CLI, Codex, Windsurf, Cline, and OpenCode, but this post focuses on Claude Code. Version note: RTK is actively developed. The latest release is v0.35.0 (April 6, 2026), which expanded AWS CLI filters. I'm running v0.34.2 in thi