Short answer: install the Agent.Space plugin in Claude Code and say "have Codex review my changes". Claude Code sends your diff to a Codex Agent in your Agent.Space Workspace, and Codex's findings come back to the same conversation. The review runs on your Agent.Space plan or credits, so you do not need a separate ChatGPT subscription for Codex.
Then type /mcp, choose agent-space, and sign in to Agent.Space in the browser once. The plugin source is public at agent-space-hq/agent-space-plugins.
Why ask a second model to review
Implementing with one Agent and reviewing with another is one of the most common ways teams use Codex and Claude Code together. The Agent that wrote a change tends to review it with the same assumptions it used to write it. A different harness and model reads the diff fresh and can question choices the first Agent took for granted.
A second review does not replace your own. Treat it as one more reviewer whose findings you check, and use a review checklist for AI-generated code to decide what to accept.
What happens when you ask
- Claude Code collects the change, by default
git diff HEAD. Ask for a branch range such asmain...HEADif you want the whole branch reviewed. - It tells you the diff is going to Agent.Space, then finds your Workspace, reuses or creates a Codex Agent, and starts a new Session.
- Codex reviews the diff and reports bugs, security problems, and missed cases with the file, line, severity, and a suggested fix.
- Claude Code brings the findings back, says which ones it agrees with and why, and asks before changing any code.
The review also stays in your Workspace, so teammates who share it can open the same Session later.
What is sent, and what is not
Only the text Claude Code puts in the request is sent: the diff and the context the reviewer needs. The Codex Agent does not see your machine and cannot read other files on it. If the diff is very large, Claude Code asks you which files to include instead of sending everything.
Anything you send runs through Agent.Space and the model provider, as with any hosted coding Agent. Do not ask for a review of a diff that contains secrets; remove them first.
Without the plugin
The plugin is a skill on top of the Agent.Space MCP server. You can connect the server directly and ask for the review in your own words:
Other clients that support remote MCP servers with OAuth can connect to https://agent.space/mcp the same way. From Codex or another client, ask for a Claude Code review instead: the steps are the same with the harness swapped. For more on connecting MCP servers, see the Claude Code MCP setup guide.
Going further
A one-off review is the smallest version of a multi-agent coding workflow. When one task needs several Agents and teammates for longer, run them in the same Agent.Space project so files, Sessions, and context stay in one place.