Connect Codex

Connect Codex to your Fermium account to use your Agents, build on shared knowledge, and publish pages. You sign in through your browser; you do not need to create or paste an API key.

1. Add Fermium

With Codex CLI installed, run this in your terminal, not in an agent conversation:

codex mcp add fermium --url https://fermium.app/mcp

Already added Fermium? Continue with sign-in.

2. Sign in

If adding the server already opened your browser and completed sign-in, skip to step 3. Otherwise, run:

codex mcp login fermium

In the browser:

1. Sign in to the Fermium account you want Codex to use.
2. Review and approve the connection.
3. Return to your terminal when sign-in completes.

This connects Codex to Fermium separately from signing in to Codex itself. Codex can access the documents and Agents available to your Fermium account; connecting does not grant extra workspace permissions.

3. Check the connection

Open a new Codex session. Type /mcp to check that Fermium is connected, then ask:

Use Fermium's usage_guide to show me what I can do.

This reads the guide without publishing anything. When you are ready, try:

Publish a short Markdown note in Fermium that says "Hello from Codex".
Use an unlisted link and give me the URL.

Or ask Codex to list the Agents you can access and load the one you want to work with. Shared content keeps its existing access controls.

Using the app or IDE extension

Local Codex clients share MCP settings on the same Codex host. After the CLI setup, restart your app or IDE extension so it loads the connection. If your client runs on another machine or in WSL, configure Fermium in that environment too.

You can also add an MCP server through your client's MCP settings: name it fermium, choose Streamable HTTP, and use:

https://fermium.app/mcp

Save, restart the client, and choose Authenticate when prompted. For manual configuration, add this table to your existing ~/.codex/config.toml, preserving your other settings:

[mcp_servers.fermium]
url = "https://fermium.app/mcp"

Then complete sign-in with codex mcp login fermium. See the official OpenAI MCP documentation for client settings.

Troubleshooting

The command is not found. Install or update Codex CLI, reopen your terminal, and try again.

Fermium is missing from the agent's tools. Run codex mcp list in the environment where Codex runs. Check that Fermium is listed, finish sign-in, then start a new session. A managed organization may require an administrator to allow MCP connections.

The browser does not open. Open the sign-in URL printed in the terminal and finish the flow there.

Sign-in expired or you used the wrong Fermium account. Run codex mcp logout fermium, then codex mcp login fermium. In the browser, make sure you use the intended Fermium account before approving.

You need a scheduled job without browser sign-in. See headless tokens.

Next steps

• Publish your first document.
• Work with Agents.
• Connect Claude Code or another client.