Codex MCP client
Does your MCP server work in Codex?
OpenAI's coding agent. Codex does not render MCP apps, and handles tool results its own way. Our catalog records the details below. Test your server against it with MCPJam.
npx @mcpjam/inspector@latestWhat Codex supports
MCP apps
Codex does not render MCP apps. Tool results come back as plain content.
Tool-result images
The model sees images returned via direct content, embedded resources, and linked resources. That covers every result shape we track.
Display
No display-mode data recorded.
MCP extensions
Advertises no MCP extensions in our catalog.
Emulation model
MCPJam emulates Codex using openai/gpt-5-nano, so tests reflect how this host actually drives your tools.
How we know
Assumed: Inferred defaults, not yet verified against the client. Last reviewed 2026-07-08.
Codex capability questions
Live support matrix for MCP sampling, per client.
Live support matrix for MCP elicitation, per client.
Live support matrix for MCP roots, per client.
The full Can I Use matrix on caniuse.dev.
How to test your MCP server against Codex
Run npx @mcpjam/inspector@latest, connect the server config you already use, and select Codex. MCPJam drives your server the way this host does, including its model (openai/gpt-5-nano), so you see the tool calls it actually makes instead of guessing from a bug report.
From there, Trace shows every step from prompt to response, the OAuth Debugger shows where authorization breaks, and Evals score whether the model picks the right tool across realistic requests. All of it runs locally, free and open source.
Frequently asked questions
No. Our catalog records Codex as not rendering MCP apps. (Assumed, last reviewed 2026-07-08.)
The model sees images returned via direct content, embedded resources, and linked resources. That covers every result shape we track.
Run npx @mcpjam/inspector@latest, connect your server, and select Codex. MCPJam emulates the host with openai/gpt-5-nano so you can watch the real tool calls, trace them, and score them with evals.
It comes from MCPJam's host-compat catalog (the same data behind caniuse.dev), recorded as "assumed" and last reviewed 2026-07-08. Inferred defaults, not yet verified against the client.
See how your server behaves in Codex.
One command, your existing server config, this host's real behavior in the loop.
Open source · no credit card · ~2 min