Two productivity plugins for Claude Code: RTK (token savings on CLI tool calls) and Caveman (compressed communication mode).

1. RTK (Rust Token Killer)
RTK is a CLI proxy that intercepts shell commands from Claude Code and rewrites them into token-optimized versions — cutting 60-90% of token usage on dev operations like `git status`, `git diff`, etc.

Install
brew install rtk
rtk --version   # verify install

Hook setup
RTK integrates with Claude Code via a PreToolUse hook on the Bash matcher. Add to ~/.claude/settings.json:

{
  "hooks": {
    "PreToolUse": [
      {
        "matcher": "Bash",
        "command": "rtk hook claude"
      }
    ]
  }
}

This intercepts every Bash tool call and transparently rewrites commands to rtk proxies (e.g. git status → rtk git status).

Documentation reference
Create ~/.claude/RTK.md with usage reference, then reference it from your CLAUDE.md:

@RTK.md

RTK.md should document:
- Meta commands (run directly, not proxied):
  - rtk gain — show token savings analytics
  - rtk gain --history — command usage history with savings
  - rtk discover — analyze Claude Code history for missed optimization opportunities
  - rtk proxy <cmd> — execute raw command without filtering (debugging)
- Hook-based usage — all other commands are automatically rewritten by the hook. No manual intervention needed.

Verify it works
rtk gain   # should show savings stats, not "command not found"

Warning: Name collision exists with reachingforthejack/rtk (Rust Type Kit). If rtk gain fails, check which rtk points to the correct binary.

2. Caveman
Caveman is a Claude Code plugin that compresses assistant communication — cutting ~75% of filler tokens while keeping full technical accuracy. Think: smart caveman who drops articles, filler words, and pleasantries but keeps every technical detail.

Install
Install from the Claude Code marketplace:
claude mcp add-from-marketplace caveman@caveman

This registers it in ~/.claude/settings.json automatically.

How it works
Caveman uses two hooks (user-level, stored in ~/.claude/hooks/):

Hook | Script | Purpose
SessionStart | caveman-activate.js | Injects "CAVEMAN MODE ACTIVE" instructions at session start
UserPromptSubmit | caveman-mode-tracker.js | Re-injects reminder per prompt, tracks intensity level

Supporting files installed alongside:
- caveman-config.js — configuration
- caveman-stats.js — token savings tracking (via /caveman-stats)
- Statusline scripts for mode display

Intensity levels
Switch with /caveman lite|full|ultra:

Level | Effect
lite | Drop filler, keep grammar mostly intact
full (default) | Drop articles, fragments OK, short synonyms
ultra | Maximum compression, telegraphic style

Skills provided
- /caveman lite|full|ultra — switch intensity
- /caveman-commit — ultra-compressed commit messages
- /caveman-review — ultra-compressed code review comments
- /caveman-compress — compress memory/doc files into caveman format
- /caveman-help — quick reference card

Disable
Say stop caveman or normal mode in conversation to revert to standard English.

Important caveat
Node path hardcoding: The hook commands may hardcode the node binary path (e.g. /opt/homebrew/Cellar/node/XX.Y.Z/bin/node). This breaks when Homebrew bumps the node version. Fix: edit the hook scripts to use plain node instead of the absolute path, so it resolves from $PATH.

Verify both are active
Start a new Claude Code session. You should see:
- SessionStart:startup hook success: CAVEMAN MODE ACTIVE — Caveman is injecting
- Bash commands getting rewritten transparently — RTK is proxying
Run rtk gain to confirm token savings are being tracked

Summary
Plugin | Install method | Integration | What it saves
RTK | Homebrew | PreToolUse hook on Bash | 60-90% tokens on CLI output
Caveman | Claude Code marketplace | SessionStart + UserPromptSubmit hooks | ~75% tokens on assistant prose