Browser AI Debate MCP

A Model Context Protocol (MCP) server that runs a structured multi-round debate between ChatGPT Web and Gemini Web by operating both in Chrome via CDP (Chrome DevTools Protocol). It uses browser automation rather than provider APIs.

What It Does

1. Opens ChatGPT Web and Gemini Web in the same Chrome session

2. Sends the same question to both models independently

3. Makes each model critique the other response

4. Requests revised answers

5. Produces a final conclusion and an independent audit

6. Returns structured results with confidence, rationale, risks, and provider status

Important

• Requires logged-in ChatGPT and Gemini browser sessions

• Uses browser UI automation, so provider UI changes can break selectors

• Does not require OpenAI or Gemini API keys

• Stores the dedicated profile only in .browser-ai-profile/, which is gitignored

• Does not terminate a user-owned Chrome process

Prerequisites

• Node.js 20 or newer

• Google Chrome desktop

Setup

git clone https://github.com/kaenozu/browser-ai-debate-mcp.git
cd browser-ai-debate-mcp
npm install
npm run build

Chrome Preparation

Auto-launch

When BROWSER_AI_CDP_URL is not set, the server attempts to launch a dedicated Chrome profile automatically.

npm start

Connect to an existing logged-in Chrome

1. Log into ChatGPT and Gemini in Chrome.

2. Enable remote debugging at chrome://inspect/#remote-debugging.

3. Configure the CDP endpoint before starting the server.

Windows Command Prompt:

set BROWSER_AI_CDP_URL=http://127.0.0.1:9222
npm start

PowerShell:

$env:BROWSER_AI_CDP_URL = "http://127.0.0.1:9222"
npm start

Pre-launch a dedicated profile

npm run login

Log into both services, close Chrome, then run:

npm run chrome:debug

Start the MCP server in another terminal:

npm start

MCP Client Configuration

The public server identifier remains browser-ai-debate, and the public tool name remains browser_ai_debate for compatibility.

Auto-launch configuration:

{
  "mcpServers": {
    "browser-ai-debate": {
      "command": "node",
      "args": ["dist/index.js"]
    }
  }
}

Existing Chrome via CDP:

{
  "mcpServers": {
    "browser-ai-debate": {
      "command": "node",
      "args": ["dist/index.js"],
      "env": {
        "BROWSER_AI_CDP_URL": "http://127.0.0.1:9222"
      }
    }
  }
}

browser_ai_debate Tool

Example input:

{
  "question": "Why is not swallowing exceptions important in TypeScript?",
  "context": "We have 70 source files and 23 try-catch blocks that swallow errors",
  "decisionCriteria": ["reliability", "debuggability", "user experience", "maintainability"],
  "maxRounds": 3,
  "timeoutMs": 900000
}

Timeout and Partial Results

• timeoutMs covers queue wait time and all debate phases

• Provider failures are returned explicitly

• If only one provider completes, the result is marked partial

• Partial output is never presented as a complete result

Security Notes

• Browser profiles and credentials are not committed to Git

• Conversation content is not sent to an additional external service by this MCP server

• User-owned Chrome is not terminated by the server

• Dedicated Chrome processes started by the server are cleaned up on shutdown

Troubleshooting

CDP connection fails

1. Confirm Chrome remote debugging is enabled.

2. Confirm BROWSER_AI_CDP_URL points to the active endpoint.

3. Check that port 9222 is available and reachable.

4. Run npm run chrome:debug to start the dedicated profile explicitly.

5. Open http://127.0.0.1:9222/json/version locally to confirm the endpoint responds.

AUTH_REQUIRED

The stored browser session has expired or is not logged into one of the providers.

1. Run npm run login.

2. Log into ChatGPT and Gemini.

3. Close the profile window and retry.

Provider UI or DOM selectors changed

Authentication succeeds, but the provider page no longer matches the expected UI.

1. Retry with a fresh dedicated profile.

2. Confirm the provider page works manually.

3. Report the provider, page state, and observed error without including credentials or private conversation content.

4. Update only the provider selector module (src/providers/<provider>/selectors.ts) and its sanitized fixture test (tests/provider-selector-smoke.test.ts). Keep fixtures free of real conversation content.

5. Run npm test and npm run check before opening a PR.

The normal CI suite runs the sanitized DOM fixture and fallback-order tests. The opt-in .github/workflows/live-smoke.yml is manual-only, checks out master, requires the protected provider-live-smoke environment, and reads only BROWSER_AI_CDP_URL from secrets. It must never be enabled for pull requests or execute untrusted PR code. Live smoke requires logged-in ChatGPT and Gemini tabs in the operator's CDP session; those checks are intentionally an external gate.

Auto-launch cannot find Chrome

Confirm Chrome is installed in a standard location, or use an explicit CDP connection with BROWSER_AI_CDP_URL.

Windows Quick Start

start.bat

Manual start:

npm run build
npm start

Interactive MCP inspection:

npm run inspector

OpenCode MCP Registration

Existing logged-in Chrome:

{
  "mcpServers": {
    "browser-ai-debate": {
      "command": "cmd",
      "args": ["/c", "node", "C:/path/to/browser-ai-debate-mcp/dist/index.js"],
      "env": {
        "BROWSER_AI_CDP_URL": "http://127.0.0.1:9222"
      }
    }
  }
}

For dedicated auto-launch mode, omit the env block.