Eulerian MCP Integration Guide for ChatGPT
EULERIAN MCP
- ChatGPT integration guide
- For users without advanced technical knowledge
- Custom connector with OAuth · developer mode · ChatGPT
1. What it is
This guide connects ChatGPT directly to Eulerian's remote MCP server. Authentication is handled through OAuth 2.1: you install nothing, you don't use the terminal, you don't edit any file and you never have to paste a token. You simply create an "app" (connector) with the server URL and sign in with your Eulerian account. The main difference from other clients is that, today, ChatGPT requires you to turn on Developer mode to add a custom MCP server.
Is this the same as Claude.ai ?The principle is identical: a remote endpoint + OAuth sign-in, with nothing to install and ChatGPT never seeing your password. The only difference is where the connector is added: in ChatGPT you do it from Settings > Apps > Advanced settings, after first enabling Developer mode.
What you can do with it:
- Check last week's paid search campaign performance with a single sentence.
- Discover which media channels drove the most conversions this month.
- Analyse the customer journey of your highest-converting segment.
- Get analytics insights without exporting data manually.
2. Before you begin
You need these four things before continuing:
1
A ChatGPT account that allows custom connectors (MCP)
Creating custom MCP apps/connectors is done from Settings > Apps. It requires turning on Developer mode. Availability may vary by plan (Plus, Pro, Business, Enterprise) and by your organisation's settings — check that your account allows it.
2
Permission to enable Developer mode
Developer mode is flagged as "HIGH RISK" because it lets you add unverified connectors. On Business/Enterprise accounts, a workspace administrator may need to enable it or add the connector at the organisation level (see Section 4).
3
Eulerian's remote MCP endpoint URL
Eulerian provides it; it looks like https://your-instance.api.eulerian.com/mcp . It must be reachable over the internet, because the connection originates from OpenAI's servers (not from your computer).
4
Your Eulerian credentials
Your Eulerian username and password. You'll sign in during the OAuth step. Unlike the desktop method, there is NO API token to paste here.
Verify against your plan and organisationMenu names and the availability of Developer mode in ChatGPT can change and depend on your plan and your organisation's policies. If you can't see an option, confirm with your account administrator before continuing.
3. Step-by-step installation
Step 1 Open Settings > Apps
In ChatGPT, open your account menu and go to Settings > Apps. This is where you manage the apps ChatGPT can use in your chats. Click Advanced settings to reach the developer options.
The "Apps" panel in Settings, with access to "Advanced settings" (screenshots shown in Spanish UI).
Step 2 Turn on Developer mode
Inside Advanced settings you'll find the Developer mode toggle, flagged as "HIGH RISK". Turn it on. Once enabled, a Create app button appears, which lets you add Eulerian's MCP server.
Advanced settings: "Developer mode" is off by default.
With "Developer mode" enabled, the "Create app" button appears.
Developer mode = high riskDeveloper mode lets you add unverified connectors that could read or modify data. Only turn it on to add a trusted connector (here, Eulerian) and turn it off when you no longer need it.
Step 3 Create the Eulerian app
Click Create app. In the New app form, enter a descriptive Name (for example "MCP Eulerian"), choose Server URL under Connection and paste the remote MCP server URL Eulerian gave you. Under Authentication, select OAuth. Accept the risk notice with "I understand and want to continue" so you can save.
The "New app" form with the name, the MCP server URL and OAuth (demo values shown).
Leave OAuth on automaticIn most cases selecting "OAuth" is enough; you don't need to fill in "Advanced OAuth configuration" unless Eulerian gives you a specific Client ID/Secret. Double-check the URL exactly as Eulerian provided it.
Step 4 Sign in with the connector
ChatGPT will ask you to connect to the app. Click "Sign in with MCP Eulerian". Eulerian's sign-in page opens, where you enter your Eulerian username and password.
The connection dialog: click "Sign in with MCP Eulerian" to start the OAuth flow.
No token to paste hereYou sign in with your own Eulerian account via OAuth 2.1. ChatGPT never sees your password: Eulerian hands it only a limited, revocable access.
Step 5 Authorize access
Eulerian shows you which permissions ChatGPT is requesting — for example eulerian:reports.read, eulerian:admin.read and eulerian:admin.write. Review them and click "Approve" to authorize (or "Deny" to cancel).
Eulerian's authorization screen: review the requested permissions and click "Approve".
Grant only the permissions you needAlways review the scopes before approving. If you only need to read reports, the minimum is eulerian:reports.read; the admin.* scopes allow reading and writing configuration, so grant them only if your use case requires it.
Step 6 Done — use it in chat
You'll see the message "MCP Eulerian has been installed" and the connector card with its details (URL, OAuth authorization type and the DEV label for Developer mode). You can now use it: in a conversation, invoke the app and ask in natural language, for example:
Connector installed: card showing permissions, connection date, URL and OAuth authorization.
Which Eulerian tools do you have access to?
ChatGPT's "Apps" gallery, where the apps available in your chats live.
Connection completeNothing installed and no tokens pasted. You can disconnect the connector at any time from Settings > Apps, and turn Developer mode off when you're done.
4. Business and Enterprise plans: organisation control
If your account is part of an organisation (Business or Enterprise), members may not be able to enable Developer mode or add connectors on their own. In that case, the workspace administrator controls these options:
- Enable (or restrict) Developer mode and custom connectors for the team.
- Add and approve the Eulerian connector at the organisation level; each user then connects individually with their own Eulerian account.
That way, ChatGPT only accesses the data each user can see in Eulerian. Check with your administrator which policy is in force before using real business data.
5. Other clients and notes on Developer mode
Because authentication uses OAuth 2.1 and is delegated to the MCP client, the same Eulerian remote endpoint works with other MCP-compatible clients. Eulerian's part — endpoint URL, OAuth sign-in and authorization — is always the same; what changes is where each platform adds the connector.
Developer mode may evolveIn ChatGPT, creating custom MCP connectors currently goes through Developer mode. OpenAI may change the name, location or requirements of these options; if something doesn't match the screenshots, check OpenAI's official help and Eulerian's documentation.
- Eulerian OAuth 2.1 (third-party integrations): doc.api.eulerian.com/#section/Introduction/OAuth-2.1-for-third-party-integrations
6. Security and best practices
OAuth instead of tokens
With the connector, no token is stored in the browser or on your computer. You authenticate with your Eulerian account and Eulerian grants ChatGPT a limited access (for example, report reading only) that is revocable at any time.
Developer mode: enable it carefully
Developer mode lets you add unverified connectors and is flagged as "HIGH RISK". Only turn it on to add trusted connectors and turn it off when you no longer need it. If you keep the "Apply CSP in developer mode" option on, apps without a declared CSP use the default restricted network policy.
Explicit, minimal permissions
Always review the permissions requested on Eulerian's authorization screen (for example eulerian:reports.read) before clicking "Approve". Grant only what's needed and avoid write scopes if you won't use them.
Trusted connectors only
Only add MCP servers from developers you trust. A connector can read and act on data, so always verify the origin of the URL: here, the developer is Eulerian.
Validate with your IT department
Before using real business data, confirm with IT which AI platforms are approved. On Business/Enterprise, centralised management of connectors and Developer mode makes this control easier.
7. If something doesn't work
I can't see "Create app" or Developer mode
Go to Settings > Apps > Advanced settings and turn on "Developer mode". If it isn't there, your plan or organisation may not allow it (see Section 4).
I can't save the app
You must accept the "I understand and want to continue" notice in the form, select "OAuth" as authentication, and make sure the server URL is exactly the one Eulerian gave you.
The connection fails or doesn't reach the server
The endpoint must be reachable over the internet: the connection leaves OpenAI's servers, not your computer. If the server is behind a firewall or VPN, it won't connect.
Eulerian rejects the sign-in
Use your Eulerian credentials (not your ChatGPT ones). If you have access to several grids, use the URL with the correct parameter Eulerian indicated.
"Permission denied" after authorizing
On Eulerian's authorization screen you must click "Approve" (not "Deny"). If you clicked "Deny", repeat the connector sign-in step.
The connector doesn't respond in chat
In Settings > Apps, check that "MCP Eulerian" is still connected, and invoke it in the conversation before asking.
8. Additional resources
- Eulerian OAuth 2.1 (third-party integrations): doc.api.eulerian.com/#section/Introduction/OAuth-2.1-for-third-party-integrations
- Eulerian MCP Server documentation: doc.eulerian.com/p/NhupKnGmQtUv_E/MCP-Server
- GitHub repository: github.com/EulerianTechnologies/eulerian-marketing-platform-mcp
- ChatGPT help on apps and connectors: help.openai.com (search "apps" / "connectors" / "developer mode")