Connect an AI agent

An AI agent such as Claude, ChatGPT, Codex or Cursor can create and edit your Fantasma projects for you. MCP, the Model Context Protocol, is the standard these AI apps use to work with other services. You add Fantasma's MCP server to your AI app with one URL, sign in to Fantasma, and choose what the app may do.

You can connect an app on Free and on Pro. Downloading and publishing a theme need Pro, for an agent as for you. Fantasma does not need to be open while the agent works.

Copy the MCP URL

1. Open your project in Fantasma.
2. Click your profile picture, the last icon in the column of icons beside the canvas. A menu opens. On the dashboard, the same picture is next to Create project.
3. Select Account settings.
4. Click Connected apps.
5. In the MCP URL field, click the copy icon. "MCP URL copied" appears.

The URL is https://www.fantasma.io/api/mcp, the same for every account, so you can also copy it from here.

Add Fantasma to your AI app

Follow the part for your app. Each part ends on Fantasma's consent page, the page described under Allow access in Fantasma.

Claude

These steps are for Claude on the web and in the Claude desktop app.

1. In Claude, open Customize, then Connectors.
2. Click Add, then Add custom connector.
3. Enter Fantasma as the name.
4. Paste the MCP URL as the server URL.
5. Click Continue.
6. On the next screen, Claude shows the sign-in settings it found. Click Continue.
7. Under Authentication, select Sign in now.
8. Under OAuth client, select Register automatically.
9. Click Add. Fantasma's consent page opens.

On a Free Claude plan, you can add one custom connector. On a Team or Enterprise plan, an owner adds the connector in Organization settings › Connectors, and you click Connect next to it in Customize › Connectors.

To use Fantasma in a chat, click + in the message box, select Connectors, and turn on Fantasma.

Claude Code

Claude Code must be installed on your computer.

1. In your terminal, run claude mcp add --transport http fantasma https://www.fantasma.io/api/mcp.
2. In Claude Code, run /mcp.
3. Select fantasma and sign in. Fantasma's consent page opens in your browser.

ChatGPT

Your ChatGPT plan and your workspace's settings decide whether you can add an MCP server.

1. Open chatgpt.com/plugins.
2. Click the plus button. A menu opens.
3. Select Add custom MCP server.
4. Enter Fantasma as the name, and a short description.
5. Under Connection, paste the MCP URL.
6. If the form asks how to sign in, choose OAuth.
7. Read the warning, and select I understand and want to continue.
8. Select Create as a plugin.
9. Install the new plugin. When ChatGPT asks you to sign in, Fantasma's consent page opens.

To use Fantasma in a chat, type @ in the message box and select Fantasma.

Codex

In the Codex app:

1. Open Settings.
2. Select MCP servers.
3. Select Add server.
4. Enter fantasma as the name.
5. Choose Streamable HTTP, and paste the MCP URL as the server URL.
6. Save the server.
7. Select Restart.
8. Select Authenticate. Fantasma's consent page opens.

In the Codex extension for your code editor, open the gear menu of the Codex panel and follow the same steps. Restart extension replaces Restart.

In the Codex command line, run these two commands. The second one opens Fantasma's consent page.

codex mcp add fantasma --url https://www.fantasma.io/api/mcp
codex mcp login fantasma

Cursor

1. Open the file mcp.json in the .cursor folder of your home folder. Create the file if it does not exist. To add Fantasma to one code project only, use .cursor/mcp.json in that project instead.
2. Add Fantasma to it. If the file already lists other servers, add the fantasma entry inside the same mcpServers brackets.

   {
     "mcpServers": {
       "fantasma": {
         "url": "https://www.fantasma.io/api/mcp"
       }
     }
   }

3. Save the file.
4. When Cursor asks you to sign in to Fantasma, follow its prompt. Fantasma's consent page opens.

Another AI app

Add the URL as a remote MCP server in your app. The app must support OAuth sign-in, because Fantasma has no API key to paste.

Allow access in Fantasma

The consent page, Connect an app, opens in your browser.

1. If the page shows Sign in, click it and sign in to Fantasma.
2. Check the details. The app's name comes from the app itself, so connect only an app you started connecting yourself. Return to shows where you go next, such as claude.ai, and Signed in as shows your Fantasma account.
3. Choose what the app may do:
   • Build: "Create and edit projects, manage files and history, preview and download themes." It is checked at first.
   • Publish: "Manage Ghost connections, publish themes and submit projects to the gallery." It is unchecked at first.
4. Click Allow access. You go back to your AI app.

The permissions apply to all the projects you own. The app now shows under Connected apps, where you can change or remove its access at any time. You can connect several apps, and each one shows there with its own permissions.

To check the connection, ask the agent "List my Fantasma projects." It answers with the names on your dashboard, or says you have none yet.

If the page shows "This request expired. Connect from your app again.", start the connection again in your AI app. If you started two connections from the same app, cancel the other one in your app first.

What an AI agent can do in Fantasma explains each permission and what the agent asks you before it acts.