Connect Gemini to 3dCMS

The Gemini app can drive 3dCMS through the same hosted connector Claude and ChatGPT use: a URL, https://3dcms.info/mcp, and a Google sign-in. Nothing to install, no token to paste. Gemini calls it a custom app.

Add the app

1. Open Connected Apps

   On the web (gemini.google.com, not the phone app), click the gear next to your name at the bottom left, then Personal Intelligence, then Connected Apps. It is not in the main settings list, which is where most people look first. Google moves these menus from time to time; if yours look different, search Gemini's help for "custom app".

2. Add a custom app

   Scroll to Custom apps. The first time, it is a box that says "Add a custom app link to get started"; after that, a button. Paste https://3dcms.info/mcp and click Next. Leave Client ID and Client secret under the advanced settings empty: 3dCMS registers Gemini on its own.

3. Sign in and Allow

   Gemini opens the 3dCMS sign-in. Use the same Google account you use for 3dCMS (a new account is created the first time, free, no credit card). The consent page says "Google wants to connect" and that the token goes to oauth-redirect.googleusercontent.com: that is Gemini, which is right. Click Allow; a short "Returning to your assistant" page sends you back to Gemini.

4. Call it with @

   In a chat, type @ and pick 3dCMS from the list, then say what you want. The thirteen 3dcms tools are then available to Gemini.

Who can use it

• A personal Google account. Not a Workspace (work or school) account.
• In the US, 18 or older. Google's current limits for custom apps.
• Keep Activity on. Gemini turns Connected Apps off while Gemini Apps Activity is off.
• Plan. Confirmed working on Google AI Plus.

Snags people hit

• No Custom apps section. One of the requirements above is not met: most often a work or school account, or Keep Activity is off. Switch to a personal account in the top right of Gemini.
• "The Google redirect URL was rejected by the server. Enter your OAuth client ID and client secret." Do not go looking for a client ID; 3dCMS does not need one. Close the dialog and add the URL again. If it happens twice, Google has changed its callback addresses: email us and we will add them, usually the same day.
• Allow does nothing. Reload the 3dCMS page and click Allow once more. If the page then says the request expired, start again from Gemini.
• Gemini does not use 3dCMS. Type @ and pick 3dCMS at the start of the message. Without the @, Gemini may answer on its own instead of calling the tools.
• Gemini asks before every change. That is Gemini's rule for custom apps, not a 3dCMS setting: any tool that changes something needs your OK in the chat.

What to ask first

• "@3dCMS list my scenes." On a new account the answer is an empty list, which is fine: it proves the sign-in worked.
• "@3dCMS make a scene called Studio with a home page that says my name in big letters, an about page a few metres away, and a sign linking them."
• "@3dCMS take a screenshot of Studio and review the design."
• "@3dCMS publish Studio." Gemini has to ask you before it goes live.

The full ten-minute version is in Your first 3D website from a chat.

The limits

• No paid generation. The hosted connector has the thirteen core tools. generate_3d and generate_material run from the editor or the local server.
• Render budget. Server-side screenshots come out of a daily budget: 10 a day on the free 3dCMS plan, more on the paid ones.
• Publishing always asks. Nothing goes public until you say yes in the chat.
• On the command line instead? Gemini CLI and Antigravity CLI take a config entry: see Other MCP clients.