You have an MCP server URL and want to connect it to your AI assistant. In Codex, you can often ask for setup directly in chat. If that does not work in your environment, use the settings. ChatGPT in a browser has different requirements from Codex running locally.
This guide covers both routes, STDIO versus Streamable HTTP, and a simple connection test. Updated October 1, 2026. We checked the Plugins dialog below in the desktop app; adding a custom server was unavailable in our mobile test.
The benefit: your AI works with your tools#
An MCP server gives your assistant functions: search a knowledge base, retrieve a calendar entry or update a record. The server's tools and your permissions determine what it can do.
After setup, you might ask: “Search my connected knowledge base for the course materials and summarize the prerequisites.” The assistant calls a suitable tool and uses the returned data. You do not have to copy the documents into chat first.
MCP is the connection protocol. A plugin can bundle an MCP server with workflow instructions called skills. Today's ChatGPT and Codex plugins are different from the earlier ChatGPT plugins.
Start by asking Codex in chat#
OpenAI explicitly explains that Codex can often help install the MCP servers you need. Start with a request like this:
Add the MCP server “OpenAI Docs” at https://developers.openai.com/mcp. Then check whether it is connected and which tools are available.
This URL belongs to OpenAI's official, read-only documentation server. It gives you a concrete example to try.
You may not need to open settings yourself. Codex still needs a supported setup capability or access to its configuration. For OAuth, you sign in to the provider yourself. A new chat or restart may be necessary afterward.
The same request may fail in a regular ChatGPT chat when no setup capability is available. Explaining how to add a server does not connect it. Ask to see the connection status and an actual tool call.
Manual setup: Settings, Plugins, MCP#
If your interface offers the Plugins dialog, follow these steps:
- Open Settings → Plugins.
- Select the MCP tab at the top. Depending on the view, you may also click Add before selecting the tab.
- Select Add MCP server.
- Enter a clear name.
- Choose Streamable HTTP if you received a URL for a remote HTTP MCP server. Switch tabs if STDIO is initially selected.
- Enter the provider's complete MCP server URL. Use its MCP endpoint, rather than the website homepage.
- Click Save or Connect, depending on the interface, and complete any requested sign-in.
- Check the status and test a read-only tool in chat.
This matches our desktop-app test. OpenAI's Codex documentation also describes Settings → MCP servers → Add server, followed by saving and restarting. If your menus differ, look for the available MCP section.
Choose STDIO or Streamable HTTP#
Streamable HTTP connects to a server through a URL. This may be a provider's server or one you host yourself. Self-hosting does not determine which option to choose.
STDIO starts a server using a program command. You need the launch command and, where required, arguments or environment variables. A URL alone is insufficient. The label is STDIO, not “Studio.”
Choose Streamable HTTP for the OpenAI Docs example. A local STDIO server does not become available in ChatGPT's browser interface just by entering its name.
ChatGPT in a browser and on mobile#
OpenAI describes setting up a custom remote MCP connection through Plugins → Plus → Add custom MCP server. Enter the server URL and the required authentication. Availability and permissions depend on your account, workspace and interface; check the current connection guide. Managed workspaces also require the relevant admin permissions.
This web setup is separate from local Codex configuration. ChatGPT on the web does not automatically use servers from your local Codex configuration file. A remote server must be reachable from the environment using it; OpenAI also describes a Secure MCP Tunnel for private servers.
The custom-server dialog described here was unavailable in our mobile test. Use a browser on your computer or a supported desktop app for setup. This does not mean MCP tools are generally unavailable on phones: OpenAI's plugin documentation says plugins already available to your account may work in Chat and Work on mobile. Local connections and “Desktop only” plugins have different limits.
Test the connection and narrow down errors#
After connecting, ask for a specific read-only task. For the Docs server, try: “Use OpenAI Docs to find the guide for setting up MCP in Codex and give me the source.”
Inspect the tool call and its result. A plausible answer alone is not proof of a connection. If it fails, check:
- Is the full MCP endpoint entered, with the correct transport?
- Is the connection enabled and sign-in complete?
- Can this environment reach the server?
- Does the app need a restart, or the newly installed plugin a new chat?
- Has your account or workspace allowed this connection?
Codex CLI also supports the documented commands:
codex mcp add openaiDeveloperDocs --url https://developers.openai.com/mcp
codex mcp list
For servers supporting OAuth, start sign-in separately with codex mcp login <server-name>. The command reference explains the options. These terminal commands are not commands for a regular ChatGPT browser chat.
Write access and StudioMeyer tools#
Start with a read-only task before requesting changes. The current developer documentation describes read and write tools in ChatGPT developer mode. Write actions require confirmation by default; remembered approvals can change that behavior. Check the tool, submitted data and intended scope.
Our product pages describe the supported Claude setup for Memory, CRM, GEO and the AI connector. This article explains general OpenAI setup routes. It does not introduce support for our products in ChatGPT or Codex.
Frequently asked questions#
Can Codex add an MCP server directly from chat?#
Yes, in a supported Codex environment, Codex can handle setup when asked. Provide a name and the MCP server URL. Sign-in, approvals or a restart may still be needed. A URL alone does not guarantee an active connection.
How do I add an MCP server manually?#
Open Settings, Plugins and the MCP tab if your interface offers it. Select Add and Add MCP server, enter a name and choose Streamable HTTP for a remote HTTP server. Enter the MCP URL, save the connection and complete any requested sign-in.
Can I set it up on my phone?#
The dialog for adding a custom MCP server described here was unavailable in our mobile test. Set it up in a browser on your computer or a supported desktop app. Plugins already available to your account may work on mobile; local connections and plugins marked Desktop only are exceptions.
What is the difference between STDIO and Streamable HTTP?#
STDIO starts a server with a program command in the client's execution environment. Streamable HTTP connects the client to an MCP server URL. A self-hosted server can also use Streamable HTTP.
Can ChatGPT change data through MCP?#
According to OpenAI's developer documentation, developer mode supports read and write tools. Availability and permissions depend on the account, workspace and interface. Write actions require confirmation by default; remembered approvals can change that behavior.
Does this mean StudioMeyer tools are supported in ChatGPT?#
Our product pages describe the supported setup for Claude. This general guide is not a new support commitment for Memory, CRM, GEO or the AI connector in ChatGPT or Codex.
