Codex mcp-server removed: migration options

How to tell this is your situation

• Your integration launches codex mcp-server or the standalone codex-mcp-server binary.
• Another agent/client expects to call Codex as an MCP tool provider.
• You are following older hosting examples rather than adding an external server to Codex.
• You need a replacement integration interface before changing the live launcher.

The official removal notice distinguishes hosting Codex as a server from connecting Codex to external tools. The current command reference also marks the old hosting command removed. Do not infer a precise installed-version cutoff from these notices alone.

Step-by-step checks

1. Identify the connection direction. Read the launcher or integration settings without editing them. An MCP client starting Codex uses the removed hosting interface. Codex starting or contacting another provider is an external-tool connection. These need different investigations.
2. Inspect external connections only if that is your case. The MCP documentation documents codex mcp list and codex mcp --help. They inspect configured connections and available management commands. Do not rebuild a working external connection merely because the old Codex hosting command was removed.
3. Choose the documented interface for the actual job. The app-server documentation describes a custom-client interface with authentication, conversations, approvals and streamed events. It points job automation and CI users toward the Codex SDK. Write down what your integration needs before assuming either route fits.
4. Plan a protocol change, not a command substitution. App-server uses its own JSON-RPC protocol, not MCP tool calls. The documented initialization sequence sends an initialize request, then an initialized notification before other requests. An existing MCP adapter therefore needs implementation work; changing its executable name is not a completed migration.
5. Test an isolated integration before touching production. Preserve the existing launcher/configuration and test the new adapter separately. Record which authentication, approval and event paths your application uses. The official notice labels app-server experimental and unsupported for production, so a successful local experiment does not establish a safe live replacement.

If it is still not working

• Record the launcher command, installed build, adapter version and first failure. Share redacted diagnostics, not API keys, tokens or complete authentication files. This keeps a missing command separate from a later protocol error.
• If Codex is connecting to external tools instead, use MCP startup troubleshooting or missing MCP tools. Those pages address another connection direction.
• Ask the integration maintainer which supported interface their next version targets. A tutorial using removed examples does not establish a maintained migration path. Avoid changing a working deployment merely to match an untested example.

FAQ

Did Codex remove all MCP support?

No. The removal notice concerns hosting Codex through the old command/binary. Codex still connects to external MCP servers. Determine which direction your setup uses before changing configuration.

Can I replace mcp-server with app-server in the same launcher?

Not as a drop-in migration. The documented protocol and initialization lifecycle differ from MCP tool calls. Your client or adapter must implement the appropriate interface, and its behavior needs separate testing.

Is the app-server alternative ready for my production integration?

The official removal notice says the command is experimental and unsupported for production workloads. This guide therefore does not recommend a production switch. Check current documentation and your maintainer’s support policy before choosing a release plan.

Known limits of this guidance

This explains documented migration boundaries, not a tested adapter for your application. No fixed release range, universal terminal error, rollback recommendation or working production replacement has been established here.

This guide is part of our Codex mcp & configuration troubleshooting.

First check whether this is a Codex service-side problem → View live Codex status.