What is chrome-local-mcp AGENTS.md?

Instructions for chrome-local-mcp, an MCP server that connects an assistant to a Windows Chrome browser through Chrome's developer connection. It supports WSL setups and keeps people involved for CAPTCHAs and verification challenges.

Setting up, testing, and registering chrome-local-mcp with Codex or the Codex command line.

They document the required Chrome startup option, build and test commands, and registration steps needed to make the browser connection available.

chrome-local-mcp AGENTS.md — Instructions file for Codex and OpenCode by thronapple: Instructions for chrome-local-mcp, an MCP server that c

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods

npx agentmods add instructions/thronapple/chrome-local-mcp/agents-md

Clone the repo

git clone --depth 1 https://github.com/thronapple/chrome-local-mcp

Made for: Codex, OpenCode.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/instructions/thronapple/chrome-local-mcp/agents-md.svg)](https://agentmods.dev/instructions/thronapple/chrome-local-mcp/agents-md)

Your own site

<a href="https://agentmods.dev/instructions/thronapple/chrome-local-mcp/agents-md"><img src="https://agentmods.dev/badge/instructions/thronapple/chrome-local-mcp/agents-md.svg" alt="Measured on agentmods" height="20"></a>

Per session 714 This file is loaded in full into every session.

When invoked 714 The same file — it is already loaded in full.

Security scan B 2 findings. Scan, not verified.

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5	$0.00714	$0.00714
Opus 5	$0.00357	$0.00357
Sonnet 5	$0.00143	$0.00143
Haiku 4.5	$0.00071	$0.00071

Measured 3d ago against content hash 974c64fa8a0a, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade B, and why

chrome-local-mcp AGENTS.md scanned grade B with 2 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 3d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Reads agent configuration directoriesmediumAgent snooping

.claude/, .codex/, .gemini/ hold keys, settings and other credentials a mod has no legitimate need for.

Edit `~/.codex/config.toml`:

Makes network callslowCapability

Not a fault in itself. Listed so you know the mod talks to something, and to what.

curl http://localhost:9222/json/version # Verify Chrome CDP is reachable

AGENTS.md · 74 lines

How it starts

The opening of the file, as written. The whole thing — 74 lines — stays where its author put it; the contents beside it link to each section on GitHub.

AGENTS.md

This file provides guidance to Codex (Codex.ai/code) when working with code in this repository.

Project Overview

chrome-local-mcp is a lightweight MCP (Model Context Protocol) server that connects to a Windows Chrome instance via CDP (Chrome DevTools Protocol). Designed for WSL environments where Codex needs to control a real browser with human-in-the-loop support for CAPTCHAs and verification challenges.

Build & Run

npm run build          # Compile TypeScript → dist/
npm run dev            # Watch mode
npm start              # Run the MCP server (requires Chrome with --remote-debugging-port=9222)

Register with Codex

Codex mcp add --scope user chrome-local -- node /mnt/d/repository/chrome-local-mcp/dist/index.js

Register with Codex CLI

Edit ~/.codex/config.toml:

[mcp_servers.chrome-local]
command = ["node", "/mnt/d/repository/chrome-local-mcp/dist/index.js"]

Test

npm test                           # Quick tool listing test
curl http://localhost:9222/json/version  # Verify Chrome CDP is reachable

Prerequisites

Windows Chrome must be running with remote debugging:

chrome.exe --remote-debugging-port=9222

Architecture

Codex (WSL) → stdio → MCP Server (WSL/Node.js) → CDP WebSocket → Chrome (Windows)

Transport: stdio (MCP standard for CLI agents)
CDP connection: chrome-remote-interface npm package, single persistent connection with auto-reconnect
Token strategy: Long content saved to temp files (/tmp/chrome-mcp/), only summaries returned to LLM context

Source Structure

src/index.ts — Entry point, CLI arg parsing, server bootstrap
src/cdp.ts — CDP connection management (connect, reconnect, target switching)
src/detect.ts — Shared challenge auto-detection (Cloudflare, CAPTCHA, login walls, etc.)
src/tools/navigation.ts — navigate, wait_for, go_back
src/tools/content.ts — get_content (smart extraction), evaluate (JS exec), screenshot
src/tools/interaction.ts — click, fill, press_key, scroll
src/tools/tabs.ts — tab_list, tab_open, tab_switch, tab_close
src/tools/search.ts — Google search with auto CAPTCHA detection
src/tools/human.ts — wait_for_human, check_page_status
src/types/chrome-remote-interface.d.ts — Type declarations for CDP client

Read the full file on GitHub · 74 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

3d ago First seen · 74 lines · 714 tokens per session scan B 974c64fa8a0a

Subscribe to this mod's changes

chrome-local-mcp AGENTS.md is an instructions file published in the GitHub repository thronapple/chrome-local-mcp (0 stars, last pushed 1mo ago), licensed MIT. It adds 714 tokens to every session, about $0.0036 per session on Opus 5. A static security scan graded it B with 2 findings (reads agent configuration directories, makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Browser automation browser-automation chrome chrome-devtools-protocol human-in-the-loop mcp

chrome-local-mcp AGENTS.md