mini-browser

Original：🇺🇸 English
Translated

Browser automation skill for AI agents using the mb CLI. Use when the agent needs to browse the web, take screenshots, scrape text, fill forms, click elements, record screencasts, run JS in pages, or audit designs. Triggers on: "browse", "open a page", "take a screenshot", "scrape", "fill form", "click button", "web automation", "record screen", "design audit", "accessibility check".

112installs
Sourcerunablehq/mini-browser
Added on

NPX Install

npx skill4agent add runablehq/mini-browser mini-browser

Tags

Translated version includes tags in frontmatter
browser-automationai-agent-toolmb-cliweb-scrapingdesign-audit

SKILL.md Content

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mini-browser (mb) — Browser CLI for Agents

mb
is a browser CLI where each command is a small Unix tool. It talks to Chrome over CDP (port 9222) via puppeteer-core.

Setup (only if not already available)

Setup is only needed when 
mb
is not installed or Chrome is not reachable. Run these checks first — if both pass, skip straight to the Command Reference.

Check if ready

bash
# 1. Is mb installed?
which mb && echo "mb: ok" || echo "mb: MISSING"

# 2. Is Chrome listening on CDP?
curl -sf http://127.0.0.1:9222/json/version > /dev/null && echo "chrome: ok" || echo "chrome: NOT RUNNING"
If both print "ok", everything is ready — go use 
mb
commands directly.

Install (only if 
mb
is missing)

bash
npm install -g @runablehq/mini-browser

Start Chrome (only if not running)

bash
mb-start-chrome
This launches Chrome with 
--remote-debugging-port=9222
, a fresh profile, and a 1024×768 window. It no-ops if Chrome is already running.
To kill and relaunch:
bash
mb-restart-chrome

Verify

bash
mb go "https://example.com" && mb text

Environment Variables

VariableDefaultDescription
CHROME_PORT
9222
CDP port
CHROME_BIN
auto-detectedPath to Chrome/Chromium binary
CHROME_PID_FILE
<scripts>/.chrome-pid
PID file location
CHROME_USER_DATA_DIR
<scripts>/.chrome-profile
Chrome profile directory

Command Reference

Navigation

CommandDescription
mb go <url>
Navigate to URL (waits for networkidle)
mb url
Print current URL
mb back
Go back
mb forward
Go forward

Observation

CommandDescription
mb text [selector]
Visible text content (default: body)
mb shot [file]
Screenshot to PNG (default: ./shot.png)
mb snap
List interactive elements with coordinates

Interaction

CommandDescription
mb click <x> <y>
Click at coordinates
mb type [x y] <text>
Type text (with coords: selects first)
mb fill <k=v...>
Fill form fields by label/name/placeholder
mb key <key...>
Press keys (Enter, Tab, Meta+a)
mb move <x> <y>
Hover at coordinates
mb drag <x1> <y1> <x2> <y2>
Drag between points
mb scroll [dir] [px]
Scroll (default: down 500)

Recording

CommandDescription
mb record start <file>
Start recording (.webm, .mp4, .gif)
mb record stop
Stop recording and save
mb record status
Check if recording is active

Tabs

CommandDescription
mb tab list
List open tabs
mb tab new [url]
Open new tab, print index
mb tab close [n]
Close tab (default: last)

Other

CommandDescription
mb js <code>
Run JavaScript in page context
mb wait <target>
Wait for ms / selector / networkidle / url:pattern
mb audit
Design audit (palette, typography, contrast, a11y, SEO)
mb logs
Stream console logs (Ctrl+C to stop)

Flags

FlagDefaultDescription
--timeout <ms>
30000Command timeout
--tab <n>
0Target tab index
--json
falseStructured JSON output
--right
falseRight-click
--double
falseDouble-click
--fps <n>
30Recording frame rate
--scale <n>
1Recording scale factor

Usage Patterns

Observe → Act loop

The standard agent loop: snapshot the page, pick an element, act on it.
bash
mb snap                          # list interactive elements with (x, y)
mb click 512 380                 # click the button at those coordinates
mb wait networkidle              # wait for the page to settle
mb snap                          # observe again

Fill and submit a form

bash
mb go "https://example.com/login"
mb fill "Email=user@example.com" "Password=hunter2"
mb key Enter
mb wait url:/dashboard

Take a screenshot

bash
mb shot page.png

Extract text

bash
mb text "main"                   # text from <main>
mb text "#content"               # text from #content
mb text                          # full body text

Run JavaScript

bash
mb js 'document.title'
echo 'document.querySelectorAll("a").length' | mb js -

Record a screencast

bash
mb record start demo.mp4 --fps 30 --scale 1
# ... interact with the page ...
mb record stop

Design audit

bash
mb audit                         # human-readable report
mb audit --json                  # structured JSON output

Dismiss overlays

Cookie banners and modals block clicks. Remove them with JS:
bash
mb js 'document.querySelector("[class*=cookie]")?.remove()'

Wait strategies

bash
mb wait 2000                     # sleep 2 seconds
mb wait ".modal"                 # wait for selector to appear
mb wait networkidle              # wait for no network activity
mb wait url:/dashboard           # wait for URL to contain string

Important Notes

  • Viewport is 1024×768. 
    snap
    only returns elements in the current viewport — scroll and snap again to find more.
  • text
    uses querySelector     — returns first match only. Use 
    text "main"
    over 
    text "p"
    for better results.
  • go
    waits for networkidle.     For heavy SPAs, follow up with 
    wait ".selector"
    .
  • type
    with coordinates triple-clicks first     to select existing text, then types the replacement.
  • fill
    field matching order:     aria-label → placeholder → name attr → id → label text → CSS selector (use 
    #
    /
    .
    /
    [
    prefix).
  • --json
    output:     
    snap
    → 
    [{role, name, x, y, state}]
    , 
    tab list
    → 
    [{index, url, title}]
    , 
    logs
    → JSON lines, 
    audit
    → full audit object.
  • Recording state is stored in 
    ~/.mb-recorder.json
    . Only one recording at a time.
  • tab close
     cannot close the last remaining tab.

Troubleshooting

ProblemFix
"Chrome not found"Set 
CHROME_BIN=/path/to/chrome
Connection refusedRun 
mb-start-chrome
first
Stale recording stateDelete 
~/.mb-recorder.json
Chrome window wrong size
mb-restart-chrome
(creates fresh profile)
Element not in snap output
mb scroll down 500
then 
mb snap
again