Eulerian MCP Integration Guide for OpenAI Codex CLI
EULERIAN MCP
Setup guide — beginner friendly
Connect Eulerian to OpenAI Codex CLI
A step-by-step, no-jargon walkthrough — from a blank machine to live Eulerian data
This guide shows you, click by click, how to connect the Eulerian Marketing Platform MCP to OpenAI Codex CLI (OpenAI's assistant that runs in a terminal window). By the end you will be able to ask Codex questions about your Eulerian data in plain language. Good news: Codex signs in with your ChatGPT account — no API key needed (although it can be used if you prefer this approach).
What you will need (5 minutes to gather):
A computer where you can install software
Your Eulerian endpoint URL and API token (ask your Eulerian contact if you don't have them, they look like https://<your>.api.eulerian.com/mcp and a long secret string)
A ChatGPT account (free or paid).
That's it.
Step 1 Install the two things Codex needs
Codex CLI needs Node.js (to install and run Codex) and Python 3.10+ (to run the small Eulerian “bridge”). Install both if you don't already have them:
- Node.js: go to https://nodejs.org , download the “LTS” version, run the installer, keep clicking Next.
- Python: go to https://www.python.org/downloads/ , download 3.10 or newer. On Windows, tick “Add Python to PATH” on the first installer screen.
Then install the Eulerian bridge. Open a terminal (Windows: press the Start button, type cmd, press Enter — a black window appears; macOS: open the Terminal app) and type:
pip install eulerian-marketing-platform
Step 2 Install Codex CLI
In the same terminal, type this and press Enter:
npm install -g @openai/codex
When it finishes, check it is there:
codex --version
You should see a version number (we tested with codex-cli 0.142.5).
Step 3 Sign in (with your ChatGPT account — no API key)
Type:
codex login
Your web browser opens. Sign in with your ChatGPT account and approve. Come back to the terminal — you are now logged in.
Why this is nice: unlike some other terminal assistants, Codex does not require you to create and paste an API key. Your normal ChatGPT login is enough.
Step 4 Tell Codex about Eulerian (edit one settings file)
Codex keeps its settings in a file called config.toml. Its location:
Windows
%USERPROFILE%\.codex\config.toml
macOS / Linux
~/.codex/config.toml
The quickest way to open it on Windows: in the terminal type notepad %USERPROFILE%\.codex\config.toml and press Enter (click “Yes” if it offers to create the file). Paste the block below, then replace the endpoint and token with your own:
[mcp_servers.eulerian-marketing-platform]command = "C:/Users/you/AppData/Local/Programs/Python/Python312/python.exe"args = ["-m", "eulerian_marketing_platform.server"]startup_timeout_sec = 60[mcp_servers.eulerian-marketing-platform.env]EMP_API_ENDPOINT = " https://your-eulerian-instance.com/mcp "EMP_API_TOKEN = "paste-your-eulerian-token-here"
Two things people trip on: (1) the section name is mcp_servers with an underscore. (2) On Windows, point command at the full path of your Python. Not sure where it is? Run python -c "import sys; print(sys.executable)" and copy what it prints. Save the file when done.
Step 5 Check the connection
Start Codex by typing codex and pressing Enter. Then type /mcp and press Enter. You should see the Eulerian server listed with its tools — about 134 tools — which means the connection works.
Codex CLI after typing /mcp: the Eulerian server is connected and 134 tools are available.
Tip: if you run codex mcp list you may see Auth: Unsupported next to the server. That is normal and harmless — it refers to Codex's own optional login system, not to Eulerian, which uses your token.
Step 6 Try it — ask for your data
Now just ask, in plain language. A good first question:
Which websites can I query with my Eulerian account?
Codex calls the Eulerian tool and lists your sites — real data, straight from your account:
Codex answering with the real list of sites from the Eulerian account (client name redacted).
That's the whole setup. From here you can ask business questions in natural language — for example “show me last week's visits” or “compare cost vs revenue this month”.
Going further — real reporting (and what we verified)
Codex doesn't just list sites; it runs full reporting queries too. Asked for a daily visits trend, it reads Eulerian's query guide, discovers the right fields, and returns a clean day-by-day table:
Codex returning a day-by-day visits trend for the last 7 days (client name redacted).
Validation note (for the record): Codex CLI was tested end to end on Windows and worked out of the box — connection, tool discovery (134 tools) and multi-step reporting all succeeded, with no API key (ChatGPT-account login).
If something doesn't work
“codex is not recognised”
Node.js isn't installed or the terminal wasn't reopened after installing it. Install Node.js, then open a fresh terminal.
Server shows but no tools / it hangs on first launch
First discovery can take 20–30 s. Keep startup_timeout_sec = 60 in the config and wait a moment.
“Python was not found”
Use the full path of python.exe in command (see Step 4).
Auth: Unsupported worries me
Ignore it — expected and harmless (see Step 5).