Show HN: Playwriter – Extension to Control Chrome via MCP and CDP (opens in new tab)

This project is similar to Playwright MCP, but with some important differences and benefits.

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1. Key differences from Playwright MCP

   1. Uses your existing Chrome tabs via an installable Chrome extension instead of launching a new browser window.
   2. Exposes only one MCP tool: `execute`, which runs arbitrary Playwright code in a sandbox.
   3. The extension communicates with the MCP via Chrome DevTools Protocol (CDP) over WebSocket.

2. Benefits

   1. Less context bloat: the LLM only needs to reason about a single tool instead of many.
   2. More capable: the agent can write any Playwright code to control the browser.
   3. Fewer resources: reuses your existing Chrome browser instead of spawning a new instance per MCP project.
   4. Human–machine collaboration: you can temporarily disable the extension to:

      * Solve CAPTCHAs
      * Unstick the LLM
      * Intervene manually when needed

3. Using it in your own scripts

   1. You can connect to the extension from your own Playwright scripts.
   2. This lets you automate tasks in your existing Chrome tabs, instead of running a separate browser instance.

4. Non-disruptive browser control

   1. The extension does not force-focus Chrome windows during interactions.
   2. You can run automation in non-headless mode without Chrome constantly stealing focus and interrupting your work.

5. Security model

   1. The extension connects to a localhost WebSocket server started by the MCP.
   2. This server proxies MCP commands to the extension.
   3. Only tabs where the extension is enabled are accessible to the MCP.
   4. Other tabs remain isolated and inaccessible to random agents.

6. Safety considerations

   1. The MCP can still cause damage if run unsupervised.
   2. You should:

      * Run it with permissions enabled, and/or
      * Keep it under active human supervision.