Does MDN MCP (experimental) work with ChatGPT (Codex)?

Q: Does MDN MCP (experimental) work with ChatGPT (Codex)?

Yes. In our test on 2026-10-23 (Codex CLI 0.162.0-alpha.17.2, mcp-remote 0.15.2, plan: ChatGPT Plus), MDN MCP (experimental) passed install, connect, tools and an agent task.

Yes. MDN MCP (experimental) passed every step of our test in ChatGPT (Codex) on Oct 23, 2026: it installed, connected, its tools were visible, and an agent used it to finish a real task.

Result

ResultPassed

Date testedOct 23, 2026

Plan tested onChatGPT Plus

App versionCodex CLI 0.162.0-alpha.17.2

Server packagemcp-remote 0.15.2

Connect timeconnect time not recorded

Modelgpt-6-luna (reasoning low)

Steps

install OK
connect OK
tools visible OK
agent task: mdn docs fact OKanswer a fact from current MDN docs fetched by the server (MDN MCP only covers web platform docs)

From our own harness run, not the maker’s claims. How we test.

Versions tested

Codex CLI 0.162.0-alpha.17.2 · mcp-remote 0.15.2 · connect time not recorded · tested Oct 23, 2026

Server package tested: mcp-remote 0.15.2 (npm, Node v20.19.2; resolved 2026-10-23)

Direct and key dependencies as resolved: express 4.22.3 · open 10.2.0 · strict-url-sanitise 0.0.1 · undici 7.30.1

All 79 resolved dependencies

accepts==1.3.8
array-flatten==1.1.1
body-parser==1.20.9
bundle-name==4.1.1
bytes==3.1.2
call-bind-apply-helpers==1.0.2
call-bound==1.0.4
content-disposition==0.5.4
content-type==1.0.5
cookie==0.7.2
cookie-signature==1.0.7
debug==2.6.9
default-browser==5.5.1
default-browser-id==5.0.1
define-lazy-prop==3.0.0
depd==2.0.0
destroy==1.2.0
dunder-proto==1.0.1
ee-first==1.1.1
encodeurl==2.0.0
es-define-property==1.0.1
es-errors==1.3.0
es-object-atoms==1.1.2
escape-html==1.0.3
etag==1.8.1
express==4.22.3
finalhandler==1.3.2
forwarded==0.2.0
fresh==0.5.2
function-bind==1.1.2
get-intrinsic==1.3.0
get-proto==1.0.1
gopd==1.2.0
has-symbols==1.1.0
hasown==2.0.4
http-errors==2.0.1
iconv-lite==0.4.24
inherits==2.0.4
ipaddr.js==1.9.1
is-docker==3.0.0
is-inside-container==1.0.0
is-wsl==3.1.1
math-intrinsics==1.1.0
media-typer==0.3.0
merge-descriptors==1.0.3
methods==1.1.2
mime==1.6.0
mime-db==1.52.0
mime-types==2.1.35
ms==2.0.0, 2.1.3
negotiator==0.6.3
object-inspect==1.13.4
on-finished==2.4.2
open==10.2.0
parseurl==1.3.3
path-to-regexp==0.1.13
proxy-addr==2.0.8
qs==6.16.1
range-parser==1.2.1
raw-body==2.5.3
run-applescript==7.1.0
safe-buffer==5.2.1
safer-buffer==2.1.2
send==0.19.2
serve-static==1.16.3
setprototypeof==1.2.0
side-channel==1.1.1
side-channel-list==1.0.1
side-channel-map==1.0.1
side-channel-weakmap==1.0.2
statuses==2.0.2
strict-url-sanitise==0.0.1
toidentifier==1.0.1
type-is==1.6.18
undici==7.30.1
unpipe==1.0.0
utils-merge==1.0.1
vary==1.1.2
wsl-utils==0.1.0

Captured with: npm ls --all --json in the npx env.

What happened in this run

Install config we used

[mcp_servers.mdn-mcp]
command = "npx"
args = ["-y", "mcp-remote", "https://mcp.mdn.mozilla.net/"]

Connection check

server answered tool calls during the task

Tools check

verified via task step: agent saw and called the server's tools

Agent task: mdn docs fact

Tool calls, in order: mdn-mcp:search

Raw details from our harness log for this run. Secrets redacted.

Set it up in ChatGPT (Codex)

Copy-paste config for every app is on the MDN MCP (experimental) page. Not connecting? ChatGPT (Codex) MCP troubleshooting.

Other apps we tested it in: Claude Code (passed) · Cursor (passed).

All MCP servers tested in ChatGPT (Codex)