browser-control-basics

name	browser-control-basics
description	Use Chromium safely and predictably in this environment. Covers MCP versus direct CDP, what counts as real browser control, and the minimum verification/reporting rules.
license	CC0-1.0

Browser Control Basics

Use this skill when a task involves driving, inspecting, or validating behavior in Chromium.

This skill defines the shared environment rules for browser control. Load it before using more specialized browser skills.

Expected browser

This setup expects browser automation to use the Chromium instance launched by:

chromium-agent

Do not launch raw chromium, google-chrome, or a fresh browser profile for agent-controlled browser work unless explicitly instructed.

Prefer the existing running Chromium session over launching a separate browser stack.

Environment note

In this environment, chrome-devtools MCP may be unavailable or disconnected even when Chromium is running and reachable over CDP.

Treat MCP availability and browser controllability as separate concerns.

Startup check

Before debugging MCP itself, first check whether the expected browser is running and reachable.

pgrep -af 'chromium.*remote-debugging|chromium-agent'

Check the CDP endpoint used by this setup:

curl -s http://127.0.0.1:9222/json/version

Adjust the port only if the local wrapper uses a different one.

If the expected browser is not running, launch it with:

chromium-agent

Allowed control paths

If the user asks for browser automation or inspection:

• use MCP when it is available and appropriate
• if MCP is unavailable, direct CDP fallback is allowed when possible
• if both MCP and CDP fail, check chromium-agent before debugging the MCP server

What does not prove control

Do not assume browser control just because:

• a Chromium process exists
• a URL opens in the browser
• a page is visible on screen

Real browser control should be verified with an actual inspection or browser action, such as:

• listing or selecting targets
• reading DOM state, console output, or network failures
• evaluating script in the page
• clicking, typing, navigating, or taking a screenshot

Reporting rule

Briefly state which control path you used:

• MCP
• direct CDP fallback
• no browser control available

Scope discipline

Use the smallest capable control path for the task.

Do not build a fresh automation stack unless:

• browser control paths are unavailable
• the task genuinely needs a dedicated scripted runner
• repeated execution makes scripting clearly worthwhile