> ## Documentation Index
> Fetch the complete documentation index at: https://agents.craft.do/docs/llms.txt
> Use this file to discover all available pages before exploring further.
# Performance and Token Optimization
> Use RTK to reduce token usage from verbose development commands
Craft Agents can route Bash tool output through [RTK](https://github.com/rtk-ai/rtk), a local CLI that compresses common development-command output before it is sent back to the model.
This is useful when a session runs commands that produce lots of repetitive text: diffs, directory listings, search results, test logs, package-manager output, and build output. RTK does not make commands run faster; it reduces how many output tokens the model has to read and pay attention to.
Craft Agents checks and permission-prompts the **original command**. RTK only changes the output path used for the model context.
## Why enable RTK?
Verbose tool output is one of the easiest ways to burn context. For example:
```bash theme={null}
git diff
rg "TODO|FIXME" .
bun test
npm install
ls -R
```
Without RTK, the full raw output is appended to the conversation. With RTK enabled, Craft Agents invokes the local `rtk` binary to rewrite eligible Bash commands so their output is compacted before it reaches the model.
Typical benefits:
* **Lower token usage** for common development commands
* **More usable context** left for code and reasoning
* **Less noise** from repetitive logs, huge diffs, and long file listings
* **Visibility in Settings** through RTK's saved-token / efficiency stats
RTK is most useful for coding and repository-maintenance sessions. It helps less for commands that already print short, targeted output.
## Requirements
* RTK installed locally as `rtk` on your system PATH
* RTK version `0.23.0` or newer
* Craft Agents v0.9.4 or newer
Craft Agents does **not** bundle RTK. It detects the `rtk` executable on PATH and invokes it locally with telemetry disabled for Craft Agents' rewrite and stats calls.
You do not need to run `rtk init` for Craft Agents. `rtk init` installs hooks for other tools; Craft Agents calls `rtk rewrite` directly when the Performance toggle is enabled.
## Enable RTK in Craft Agents
1. Install RTK for your operating system.
2. Open **Settings → AI → Performance** and click **Re-check**. If you edited PATH environment variables, restart Craft Agents first so the desktop process sees the new PATH.
3. Enable **Token Optimization**.
4. Run a command-heavy session.
5. Return to **Settings → AI → Performance** to view saved-token stats once RTK has processed commands.
If Craft Agents still shows **Get RTK**, the `rtk` binary is either missing, below the required version, or not visible on the PATH used by the desktop app.
## Install RTK
Homebrew is the simplest option:
```bash theme={null}
brew install rtk-ai/tap/rtk
```
Or use RTK's install script:
```bash theme={null}
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/master/install.sh | sh
```
Verify:
```bash theme={null}
which rtk
rtk --version
rtk gain
```
Homebrew on Linux:
```bash theme={null}
brew install rtk-ai/tap/rtk
```
Or use RTK's install script:
```bash theme={null}
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/master/install.sh | sh
```
If you prefer Cargo:
```bash theme={null}
cargo install --git https://github.com/rtk-ai/rtk rtk
```
Verify:
```bash theme={null}
which rtk
rtk --version
rtk gain
```
Download the Windows zip from the [RTK releases page](https://github.com/rtk-ai/rtk/releases), extract `rtk.exe`, and copy it to a directory on the **Windows** PATH.
The no-admin, no-environment-edit option is to use the per-user `WindowsApps` folder. It is normally already on the Windows PATH, so it avoids administrator rights and global system folders:
```powershell theme={null}
Copy-Item "C:\Users\\bin\rtk.exe" "$env:LOCALAPPDATA\Microsoft\WindowsApps\rtk.exe" -Force
```
Verify from a new PowerShell window:
```powershell theme={null}
Get-Command rtk
rtk --version
rtk gain
```
If you prefer a dedicated user bin folder, add it to your Windows user PATH once:
```powershell theme={null}
[Environment]::SetEnvironmentVariable(
"Path",
[Environment]::GetEnvironmentVariable("Path", "User") + ";C:\Users\\bin",
"User"
)
```
Then reopen PowerShell and verify again. If Craft Agents was already running when you edited PATH, restart Craft Agents before clicking **Re-check**.
Git Bash/MSYS PATH and Windows/PowerShell PATH are not the same thing. `rtk` may work in Git Bash from `C:\Users\\bin` while Craft Agents or PowerShell still cannot find it. Put `rtk.exe` somewhere on the Windows PATH, such as `%LOCALAPPDATA%\Microsoft\WindowsApps`, or add your bin folder to the Windows user PATH.
## Windows PowerShell notes
If you are verifying from Windows PowerShell 5.1:
* Use `Get-Command rtk` or `where.exe rtk`; `which` is not a PowerShell command.
* Use `;` between commands instead of Bash-style `&&`.
Example:
```powershell theme={null}
Get-Command rtk; rtk --version; rtk gain
```
## Troubleshooting
Click **Re-check** in **Settings → AI → Performance**. If it still fails, verify `rtk` from the same operating-system shell Craft Agents can see:
* macOS/Linux: `which rtk && rtk --version`
* Windows: `Get-Command rtk; rtk --version`
On Windows, make sure the folder is on the Windows PATH, not only on Git Bash/MSYS PATH.
Check the version. Craft Agents requires RTK `0.23.0` or newer because it depends on `rtk rewrite`.
Make sure you installed Rust Token Killer (`rtk-ai/rtk`), not the unrelated Rust Type Kit package with the same binary name. The correct RTK supports `rtk gain`.
No. Craft Agents does not require `rtk init`; it uses the installed `rtk` binary directly. You only need `rtk init` if you also want RTK hooks for another tool that uses RTK that way.