rtk

---

rtk filters and compresses command outputs before they reach your LLM context. Single Rust binary, 100+ supported commands, <10ms overhead.

What RTK Does

RTK intercepts shell commands and compresses their output before your agent reads it.

Operation	What RTK does to the output
ls / tree	Tree format with file counts instead of one line per entry
cat / read	Smart file reading: signatures and structure over full bodies
grep / rg	Truncates long lines, groups matches by file
ast-grep	Groups structural matches by file, caps overflow
git status	Compact stat format, grouped by state
git diff	Reduced context, headers stripped
git log	Hash, author and subject only
git add/commit/push	Confirmation line instead of full progress output
cargo test / npm test	Failures only, passing tests collapsed to a count
ruff check	Grouped by rule and file
sqlfluff lint	Grouped by rule and file
pytest	Failures only, traceback trimmed
go test	NDJSON parsed, failures only
docker ps	Essential fields only

How Savings Work

RTK cuts up to 90% of the bash output your agent reads. That is what RTK measures, and it is not the same as cutting your bill by 90%.

Bash output is one contributor to input tokens, alongside your prompt, the system prompt and conversation history. Input tokens are in turn only part of the bill, which also counts output tokens. The reduction dilutes at every step.

The token counts RTK reports are estimated as bytes / 4 — RTK ships no tokenizer, so the percentages are reliable but the absolute token numbers are approximate.

Full explanation: How RTK Savings Work

Installation

Homebrew (recommended)

brew install rtk

winget (Windows)

Easiest way to install on Windows — one command, no PATH setup needed:

winget install rtk-ai.rtk

Quick Install (Linux/macOS)

curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh

Installs to ~/.local/bin. Add to PATH if needed:

echo 'export PATH="$HOME/.local/bin:$PATH"' >> ~/.bashrc  # or ~/.zshrc

Cargo

cargo install --git https://github.com/rtk-ai/rtk

Pre-built Binaries

Download from releases:

• macOS: rtk-x86_64-apple-darwin.tar.gz / rtk-aarch64-apple-darwin.tar.gz
• Linux: rtk-x86_64-unknown-linux-musl.tar.gz / rtk-aarch64-unknown-linux-gnu.tar.gz
• Windows: rtk-x86_64-pc-windows-msvc.zip

Windows users: Extract the zip and place rtk.exe somewhere in your PATH (e.g. C:\Users\<you>\.local\bin). Run RTK from Command Prompt, PowerShell, or Windows Terminal — do not double-click the .exe (it will flash and close). The full hook system works natively on Windows (and in WSL). See Windows setup below for details.

Verify Installation

rtk --version   # Should show "rtk 0.28.2"
rtk gain        # Should show the savings dashboard

Name collision warning: Another project named "rtk" (Rust Type Kit) exists on crates.io. If rtk gain fails, you have the wrong package. Use cargo install --git above instead.

Quick Start

# 1. Install for your AI tool
rtk init -g                     # Claude Code / Copilot (default)
rtk init -g --gemini            # Gemini CLI
rtk init -g --codex             # Codex (OpenAI)
rtk init -g --agent cursor      # Cursor
rtk init -g --agent windsurf    # Windsurf
rtk init --agent cline          # Cline / Roo Code
rtk init --agent kilocode       # Kilo Code
rtk init --agent antigravity    # Google Antigravity
rtk init --agent kimi           # Kimi AI
rtk init -g --agent pi          # Pi
rtk init --agent omp            # Oh My Pi (OMP)
rtk init --agent hermes         # Hermes
rtk init -g --agent droid       # Factory Droid
rtk init --agent trae           # Trae (project: .trae/hooks.json)
rtk init -g --agent trae        # Trae global: ~/.trae and existing ~/.trae-cn

# 2. Restart your AI tool, then test
git status  # Automatically rewritten to rtk git status

Hook-based agents rewrite Bash commands (e.g., git status -> rtk git status) before execution. Plugin-based agents, including Hermes, use their plugin API to rewrite commands before execution. The agent receives compact output without needing to call rtk explicitly.

Important: the hook only runs on Bash tool calls. Claude Code built-in tools like Read, Grep, and Glob do not pass through the Bash hook, so they are not auto-rewritten. To get RTK's compact output for those workflows, use shell commands (cat/head/tail, rg/grep, find) or call rtk read, rtk grep, or rtk find directly.

How It Works

  Without rtk:                                    With rtk:

  Claude  --git status-->  shell  -->  git         Claude  --git status-->  RTK  -->  git
    ^                                   |            ^                      |          |
    |         full raw output           |            |  compact output      | filter   |
    +-----------------------------------+            +------- (filtered) ---+----------+

Four strategies applied per command type:

1. Smart Filtering - Removes noise (comments, whitespace, boilerplate)
2. Grouping - Aggregates similar items (files by directory, errors by type)
3. Truncation - Keeps relevant context, cuts redundancy
4. Deduplication - Collapses repeated log lines with counts

Does RTK break Claude's prompt cache? No. RTK filters output once per command. The result is stored in history and cached normally on subsequent API calls, so the cache keeps working as expected. Smaller outputs also mean cheaper cache writes and reads. See Troubleshooting for details.

Commands

Percentages below are reductions in bash output, not reductions in your bill. See How Savings Work.

Files

rtk ls .                        # Compact directory tree
rtk read file.rs                # Smart file reading
rtk read file.rs -l aggressive  # Signatures only (strips bodies)
rtk smart file.rs               # 2-line heuristic code summary
rtk find "*.rs" .               # Compact find results
rtk grep "pattern" .            # Grouped search results
rtk diff file1 file2            # Condensed diff (exit 1 if files differ)

Git

rtk git status                  # Compact status
rtk git log -n 10               # One-line commits
rtk git diff                    # Condensed diff
rtk git add                     # -> "ok"
rtk git commit -m "msg"         # -> "ok abc1234"
rtk git push                    # -> "ok main"
rtk git pull                    # -> "ok 3 files +10 -2"

GitHub CLI

rtk gh pr list                  # Compact PR listing
rtk gh pr view 42               # PR details + checks
rtk gh issue list               # Compact issue listing
rtk gh run list                 # Workflow run status

Test Runners

rtk jest                        # Jest compact (failures only)
rtk vitest                      # Vitest compact (failures only)
rtk playwright test             # E2E results (failures only)
rtk pytest                      # Python tests (-90%)
rtk phpt                        # PHP .phpt tests (run-tests.php, -99%)
rtk go test                     # Go tests (NDJSON, -90%)
rtk cargo test                  # Cargo tests (-90%)
rtk rake test                   # Ruby minitest (-90%)
rtk rspec                       # RSpec tests (JSON, -60%+)
rtk err <cmd>                   # Filter errors only from any command
rtk test <cmd>                  # Generic test wrapper - failures only (-90%)

Build & Lint

rtk lint                        # ESLint grouped by rule/file
rtk lint biome                  # Supports other linters
rtk sqlfluff lint               # SQL linting (JSON, -75%)
rtk sqlfluff lint models/       # Lint a specific directory (pass path after `lint`)
rtk tsc                         # TypeScript errors grouped by file
rtk next build                  # Next.js build compact
rtk prettier --check .          # Files needing formatting
rtk cargo build                 # Cargo build (-80%)
rtk cargo clippy                # Cargo clippy (-80%)
rtk ruff check                  # Python linting (JSON, -80%)
rtk golangci-lint run           # Go linting (JSON, -85%)
rtk rubocop                     # Ruby linting (JSON, -60%+)
rtk mvnd verify                 # Maven Daemon (same filters as rtk mvn)
rtk sbt test                    # ScalaTest output (-90%)
rtk sbt compile                 # Compilation errors only (-75%)
rtk sbt run                     # Strip SBT preamble noise

Package Managers

rtk pnpm list                   # Compact dependency tree
rtk uv run pytest               # Preserve uv env, keep program output
rtk pip list                    # Python packages (auto-detect uv)
rtk pip outdated                # Outdated packages
rtk bundle install              # Ruby gems (strip Using lines)
rtk prisma generate             # Schema generation (no ASCII art)

Runtimes

rtk bun install                  # Strip progress and version lines
rtk bun test                     # Failures only (-90%)
rtk bun build                    # Errors only when writing to disk, else passthrough
rtk bunx tsc                     # Smart routing to tsc filter
rtk deno test                    # Failures only (-90%)
rtk deno lint                    # Strip download lines + tee recovery
rtk deno check                   # Strip download lines + tee recovery

AWS