# Give Claude or Cursor a cloud sandbox, a database and a publish button over MCP

> Source: <https://dev.to/mythex/give-claude-or-cursor-a-cloud-sandbox-a-database-and-a-publish-button-over-mcp-17oa>
> Published: 2026-10-26 18:31:13+00:00

Coding agents in Claude, Cursor and Codex are good at writing code. They're weaker at everything around it: a machine to run the app on, a live preview, a database, file storage, secrets and a public URL at the end. Usually you wire that up yourself.

This post shows how to hand all of that to the agent through one remote MCP server. I build Mythex, an AI app builder from Dubai, and this is how its MCP server works. The pattern applies to any MCP server that exposes a sandbox.

Once connected, the client can:

`bash`
`set_run_config`, `start_preview`, `get_preview`)
Every tool result includes a `workspace_url`, so you can watch the live preview in the browser while the agent works in your editor.

`https://mcp.mythex.ai/mcp`
Add the server with only the URL (`.cursor/mcp.json`):

```
{
  "mcpServers": {
    "mythex": {
      "url": "https://mcp.mythex.ai/mcp"
    }
  }
}
```

Toggle it on, click **Connect** when Cursor prompts, and approve in the browser. There are no API keys to paste: it's OAuth with refresh tokens.

Create a new Mythex project called "booking-demo": a React + TypeScript app where clients book 30-minute slots. Store bookings in Postgres, start the preview, check it in the browser and send me a screenshot. When it works, publish it.

The agent creates the project, writes the code in the sandbox, adds the database, starts the preview, checks it with a browser run, and publishes. You get back a preview URL, screenshots and a public URL.

`upgrade_url` instead of running.
If you'd rather build in a chat UI, the same projects open in the Mythex web app. It also works in Arabic and 68 other languages.