---
name: add-rtk
description: Install rtk token-compression proxy into agent containers. Routes Bash tool calls through rtk for 60–90% token savings on dev commands (git, cargo, pytest, docker, kubectl, etc.).
---
# Add rtk
Install [rtk](https://github.com/rtk-ai/rtk) — a CLI proxy delivering 60–90% token savings on common dev commands (git, cargo, pytest, docker, kubectl, etc.) — and wire it transparently into agent containers via the Claude Code `PreToolUse` hook.
## What this sets up
- `rtk` binary at `~/.local/bin/rtk` on the host
- `~/.local/bin/rtk` mounted read-only at `/usr/local/bin/rtk` inside the target agent group's containers
- `PreToolUse` hook in the agent group's `settings.json` so every Bash call is automatically filtered through rtk — no CLAUDE.md instructions needed
## Step 1 — Install rtk on the host
```bash
curl -fsSL https://raw.githubusercontent.com/rtk-ai/rtk/refs/heads/master/install.sh | sh
```
If the script put the binary elsewhere, move it:
```bash
find ~/.local ~/.cargo/bin ~/bin -name rtk 2>/dev/null
mv "$(which rtk 2>/dev/null)" ~/.local/bin/rtk
```
Verify:
```bash
~/.local/bin/rtk --version
chmod +x ~/.local/bin/rtk # if needed
```
## Step 2 — Identify the target agent group
```bash
ncl groups list
```
Note the group ID (e.g. `ag-1776342942165-ptgddd`). Repeat Steps 3–5 for each group.
## Step 3 — Mount rtk into the container config
`additional_mounts` is a JSON column not exposed via `ncl config update`. Update it directly via the DB helper, merging with any existing mounts.
Read current mounts first:
```bash
pnpm exec tsx scripts/q.ts data/v2.db \
"SELECT additional_mounts FROM container_configs WHERE agent_group_id = '<group-id>'"
```
Then write the merged array (include all existing entries plus the rtk entry):
```bash
pnpm exec tsx scripts/q.ts data/v2.db \
"UPDATE container_configs SET additional_mounts = '<merged-json>' WHERE agent_group_id = '<group-id>'"
```
The rtk entry to append: `{"hostPath":"/home/<user>/.local/bin/rtk","containerPath":"/usr/local/bin/rtk","readonly":true}`
Verify:
```bash
pnpm exec tsx scripts/q.ts data/v2.db \
"SELECT additional_mounts FROM container_configs WHERE agent_group_id = '<group-id>'"
```
## Step 4 — Add the PreToolUse hook to settings.json
Each agent group has a `settings.json` at:
```
data/v2-sessions/<group-id>/.claude-shared/settings.json
```
This file is mounted at `/home/node/.claude/settings.json` inside the container and is read by Claude Code for hooks, env, and model config.
Add the `PreToolUse` entry using `jq` to merge safely:
```bash
SETTINGS="data/v2-sessions/<group-id>/.claude-shared/settings.json"
jq '.hooks.PreToolUse = [{"matcher":"Bash","hooks":[{"type":"command","command":"rtk hook claude"}]}]' \
"$SETTINGS" > /tmp/rtk-settings.json && mv /tmp/rtk-settings.json "$SETTINGS"
```
If `PreToolUse` already exists, append instead of overwriting:
```bash
jq '.hooks.PreToolUse += [{"matcher":"Bash","hooks":[{"type":"command","command":"rtk hook claude"}]}]' \
"$SETTINGS" > /tmp/rtk-settings.json && mv /tmp/rtk-settings.json "$SETTINGS"
```
## Step 5 — Restart the container
```bash
ncl groups restart --id <group-id>
```
No `--message` needed — the hook is transparent and requires no agent awareness.
## Verify
Ask the agent to run `git status` or any other supported command. rtk intercepts it silently. Check savings with:
```bash
~/.local/bin/rtk gain
```
## Troubleshooting
### `rtk: command not found` inside the container
Mount wasn't applied or container wasn't restarted:
```bash
pnpm exec tsx scripts/q.ts data/v2.db \
"SELECT additional_mounts FROM container_configs WHERE agent_group_id = '<group-id>'"
# Look for entry with /usr/local/bin/rtk
ncl groups restart --id <group-id>
```
### Hook not firing
Verify the hook is in `settings.json`:
```bash
jq '.hooks.PreToolUse' data/v2-sessions/<group-id>/.claude-shared/settings.json
```
If missing, re-run Step 4.
### Binary won't execute — permission denied
```bash
chmod +x ~/.local/bin/rtk
```