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OpenAI makes ChatGPT, Codex and the OpenAI API, and it supports the Model Context Protocol (MCP) across all three. It is also a co-founder of the Agentic AI Foundation, the neutral home of MCP, where it contributed the AGENTS.md format.
Checked against: OpenAI's guide to adding a custom MCP server on 28 October 2026. eSEOspace did not test OpenAI's products.
Key Takeaways
- OpenAI co-founded the Agentic AI Foundation (AAIF) with Anthropic and Block in December 2025 and contributed AGENTS.md.
- In ChatGPT, you add a remote MCP server from the Plugins page with "Add custom MCP server," then create it as a plugin.
- Codex and the ChatGPT desktop app share one MCP configuration and support local stdio and Streamable HTTP servers.
- The Responses API has an
mcptool type, and OpenAI says there is no extra fee per tool call beyond tokens. - OpenAI's pricing and help pages blocked our checker, so plan availability for custom MCP servers is not confirmed here.
At a glance
| Item | Details |
|---|---|
| Company | OpenAI |
| What it offers for MCP | MCP clients in ChatGPT (as plugins), the ChatGPT desktop app, Codex, the Responses API and the Agents SDK |
| Who it's for | ChatGPT users and workspaces, developers on the OpenAI API, and MCP server builders |
| Open source? | MCP is open source; ChatGPT and Codex are commercial products; the Agents SDK is published on GitHub |
| Pricing | API: token costs only for MCP tool use; ChatGPT plan details not confirmed |
What OpenAI offers for MCP
Foundation role
The Linux Foundation's AAIF launch release names AGENTS.md as OpenAI's founding contribution. It describes AGENTS.md as a "simple, universal standard that gives AI coding agents a consistent source of project-specific guidance." The same release calls OpenAI an early adopter of MCP. The AAIF About page lists OpenAI's Nick Cooper on both the Governing Board and the Technical Committee. Our explainer on who owns MCP has the full picture.
ChatGPT plugins
OpenAI now packages MCP connections in ChatGPT as plugins. Its custom MCP server guide gives these steps:
- Go to ChatGPT Plugins and select the plus button.
- Choose Add custom MCP server.
- Enter a name and a server URL, or select Tunnel for a private server.
- Set up authentication, review the risk warning and select Create as a plugin.
The guide says ChatGPT "supports both read and write tools" and accepts SSE and streaming HTTP. Write actions require confirmation by default. Secure MCP Tunnel connects a private server without exposing it to the public internet.
Plugins can also show interactive UI. OpenAI's plugin docs say ChatGPT implements the open MCP Apps standard, which grew out of OpenAI's Apps SDK and the MCP-UI project, according to the official MCP blog. Our guide to MCP extensions explains MCP Apps.
Codex and the ChatGPT desktop app
OpenAI's MCP page for ChatGPT and Codex says the ChatGPT desktop app, Codex CLI and IDE extension "share MCP configuration." They support local stdio servers and Streamable HTTP servers with bearer tokens or OAuth. Settings live in ~/.codex/config.toml, and the CLI uses codex mcp add.
Codex can no longer act as an MCP server itself. OpenAI's removal notice says the codex mcp-server command was removed, while connecting Codex to external servers is still supported.
Responses API and Agents SDK
The Responses API MCP guide adds an mcp tool type with a server_url, or a tunnel_id for private servers. By default, OpenAI asks for approval before sending data to a remote MCP server. Developers can relax that per tool.
The OpenAI Agents SDK MCP docs cover hosted MCP tools, Streamable HTTP, SSE and stdio servers, plus tool filtering.
Who it's for
- ChatGPT users and workspaces that want internal tools in chat.
- Developers on the Responses API or Agents SDK.
- Engineering teams using Codex.
- Server builders who want a listing in the shared ChatGPT and Codex plugin directory.
Pricing
MCP itself is free and open source. For the API, the Responses API guide says you "only pay for tokens used when importing tool definitions or making tool calls," with no extra fee per call.
For ChatGPT, we could not confirm which plans can add custom MCP servers. OpenAI's ChatGPT pricing page and help center returned 403 errors to our checker on 28 October 2026. The developer guide says "workspace permissions and security restrictions, including Lockdown, apply." Check your own plan and workspace settings.
Security and trust
OpenAI's docs say custom MCP servers "are not developed or verified by OpenAI." The custom server guide warns that an untrusted server "may access or steal information" or trick ChatGPT into changing or deleting data.
OpenAI says ChatGPT treats tools without a readOnlyHint annotation as write actions, which need confirmation. In the API, approvals are on by default. OpenAI recommends official servers hosted by the service provider and asks people to report malicious servers to security@openai.com. Read our overview of MCP security risks before you connect business systems.
Alternatives
- Anthropic and MCP: the creator of MCP and its Claude clients.
- Microsoft and MCP: MCP in Copilot Studio, Microsoft 365 Copilot and VS Code.
- Which AI apps support MCP: a plain-English rundown of every major client.
Next step
If your team runs on ChatGPT, test one read-only server as a personal plugin before you share it with a workspace. To compare OpenAI with the other companies behind MCP, browse our MCP company spotlights. If you need a server built for your product, see our MCP development service.
Frequently asked questions
Does ChatGPT support MCP?
Yes. OpenAI's docs describe adding a remote MCP server from ChatGPT Plugins with "Add custom MCP server," then creating it as a plugin. Read and write tools are supported, and write actions need confirmation by default.
Do I still need Developer mode to add an MCP server to ChatGPT?
OpenAI's current developer guide, checked 28 October 2026, does not mention Developer mode. It starts from the Plugins page instead. Some third-party guides still describe the older Developer mode flow.
Did OpenAI create MCP?
No. Anthropic created MCP and donated it to the Agentic AI Foundation. OpenAI co-founded that foundation, contributed AGENTS.md, and holds seats on its board and technical committee.
Can Codex use MCP servers?
Yes. Codex connects to external MCP servers through config.toml or the codex mcp add command. Running Codex itself as an MCP server has been removed, according to OpenAI's docs.
