ChatGPT Review for Claude

Have ChatGPT review Claude's drafts as your editor, without leaving Claude Desktop.

Quick start

About 10 minutes, once, on your computer (Windows or Mac):

1. Install Codex and sign in with your ChatGPT account. Step 1.

2. Install the extension in Claude Desktop. Step 2.

3. Save your editor instructions as a file and choose it in the extension's settings. Step 3.

4. Ask Claude to "check my ChatGPT setup". It should say Ready. Step 4.

Related MCP server: claude-code-codex-agents

What it does

The extension adds these to Claude Desktop:

It works through the OpenAI Codex CLI, so it uses your ChatGPT subscription. You don't need an API key.

Before you use this at work: everything you send through these tools (the document, your editor instructions, the focus, rubric, question and context) goes to OpenAI and is handled under your ChatGPT account's terms and data settings. Sign in to Codex with your company's ChatGPT workspace account, and check that your company's AI policy allows sharing that material with OpenAI. If in doubt, don't send confidential, customer or personal data.

Setup

1. Install Codex and sign in

Windows: open PowerShell (Start menu → type PowerShell) and paste:

powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"

Mac: open Terminal and paste:

curl -fsSL https://chatgpt.com/codex/install.sh | sh

Those are OpenAI's official installers. If you already have Node.js, npm install -g @openai/codex also works.

Then, in a new PowerShell or Terminal window, sign in:

codex login

Choose Sign in with ChatGPT. For work documents, use your company's ChatGPT workspace account so its data settings apply. You only do this once.

2. Install the extension

1. Download codex-review-mcp.mcpb.

2. Double-click the file, or in Claude Desktop open Settings → Extensions → Advanced settings → Install Extension… and choose it.

3. Claude asks you to confirm and shows the extension's settings. You'll fill in the editor instructions file in the next step.

You don't need to install Node.js. Claude Desktop runs the extension with its own built-in copy.

3. Add your editor instructions

ChatGPT reviews as your editor when you give it your editor instructions.

1. Copy the instructions from your ChatGPT editor skill, or from the custom GPT or project you use for editing.

2. Paste them into a plain text file and save it somewhere permanent, for example Documents\ChatGPT editor.md. A SKILL.md file works as it is. The --- header block at the top is ignored. If you don't have editor instructions yet, start from the example.

3. In Claude Desktop, open Settings → Extensions → ChatGPT Review (via Codex) → Configure. Set Editor instructions file to that file and save.

The file is read for every review, so you can edit it at any time without reinstalling. If you leave the setting blank, ChatGPT uses a general-purpose reviewer.

4. Check it works

In a new Claude chat, type: Check my ChatGPT setup.

Claude runs chatgpt_check, which sends ChatGPT a one-word test question. You should see Ready and the name of your editor instructions file. If you see Not ready, the message says what to fix. See also Troubleshooting.

Using it

Write a paper. In a new chat, click +, choose Write a paper with ChatGPT as editor, and fill in the brief. For example: "A two-page proposal to move the team to fortnightly releases, for the leadership team. Use the attached notes." Attach any source files to the chat. To change the number of editor rounds, fill in rounds, from 1 to 5.

If the + menu doesn't show it, type the request instead: "Write a two-page proposal on … using the attached notes. Have ChatGPT review it with chatgpt_review, apply the edits you agree with, do two rounds, then give me a Word document and a log of the edits."

To get the Word document, Claude needs file creation turned on in Claude's settings (under Capabilities). Without it, Claude gives you the final paper as text.

If you have a Claude writing skill or project instructions, Claude follows them when drafting and when deciding which edits to accept.

Review a draft you already have. Paste it or attach it and say: "Ask ChatGPT to review this."

Long reviews

Claude Desktop stops waiting for a tool after about a minute. Long reviews take longer than that, so each tool waits up to 45 seconds. If ChatGPT is still working, the tool replies with a job ID, and Claude collects the review with chatgpt_result. This happens automatically, and you'll see Claude make a second call.

Settings

Set these in the extension's settings, or as environment variables if you use the config-file setup.

Limits

• Your ChatGPT plan's limits apply. Each review counts as one Codex task against your plan's Codex usage limits. Heavy use can hit the plan's rate limit, so wait or ask for a higher plan.

• Speed: a short review takes about 20–60 seconds, and a long paper can take a few minutes.

• Size: inputs above the size cap are rejected. Send the relevant section instead.

• Text only. Claude passes the document as text. It reads attached Word and PDF files first.

Does it work in Claude's Cowork mode?

It works in normal Claude Desktop chats. In Cowork, it only works for sessions that run on your computer, and new Cowork sessions run in the cloud by default.

What Anthropic's documentation says (checked October 2026):

• Local MCP servers and .mcpb desktop extensions run only in the Claude Desktop app, not on the web or mobile (When to use desktop and web connectors; Getting started with local MCP servers).

• Cowork sessions run in the cloud by default, and local MCP servers don't run there (Claude Cowork architecture overview).

• Local MCP servers, including .mcpb bundles, "load when the Cowork session runs on your computer" (Plugin feature support across platforms).

• On company-managed PCs, IT can turn off local MCP servers and extensions (isLocalDevMcpEnabled, isDesktopExtensionEnabled) (Enterprise configuration). If the install option is missing or greyed out, ask IT.

Troubleshooting

How it works and safety

• Each call runs codex exec --skip-git-repo-check --sandbox read-only --ephemeral in a fresh, empty temporary folder. That folder is deleted afterwards, along with the answer file Codex writes there (--output-last-message). The prompt tells ChatGPT not to run commands or edit files, and your editor instructions are included in the prompt text, so Codex doesn't need to open any files.

• The document goes to Codex on stdin, never on the command line. Processes start without a shell, so document text can't be interpreted as commands. On Windows, the server runs the codex.exe that npm installs behind its codex.cmd wrapper. If it can't find that file, it falls back to cmd.exe with only fixed, validated arguments.

• --ephemeral means Codex doesn't save the session on disk. OpenAI still receives and processes the content.

• Long jobs live only in the extension's memory. Finished results are kept for an hour so Claude can collect them, and are lost if Claude restarts.

Config-file setup (developers)

Instead of the .mcpb, you can clone the repo, run npm ci && npm run build, then add the server in Settings → Developer → Edit Config:

{
  "mcpServers": {
    "chatgpt-review": {
      "command": "node",
      "args": ["C:\\Users\\YOU\\codex-review-mcp\\dist\\index.js"],
      "env": { "CODEX_REVIEW_INSTRUCTIONS": "C:\\Users\\YOU\\Documents\\ChatGPT editor.md" }
    }
  }
}

Development

npm ci
npm test            # unit + MCP protocol tests with a fake codex (no network)
npm run e2e         # real review through your logged-in codex
npm run pack:mcpb   # builds codex-review-mcp.mcpb

CI runs the tests on Ubuntu, macOS and Windows. Pushing a v* tag builds the .mcpb and attaches it to a GitHub release.

MIT licence.