Mythex

Remote MCP server for the Mythex AI app builder: Claude, Cursor or Codex create projects, edit code and run bash in a cloud sandbox, preview, add a Postgres database and publish to a live URL.

View on mythex.ai

Hosted MCP Server

npx add-mcp 'https://mcp.mythex.ai/mcp'

Installs into Claude Code, Codex, Cursor and more

Documentation

MCP (Claude, Codex, Cursor)

How to connect Claude, Codex or Cursor to Mythex over MCP — paste the MCP URL, click Connect, approve on Mythex. Tool calls need a Pro account and credits.

MCP — build from Claude, Codex, or Cursor

Mythex exposes a remote MCP server. External agents (Claude, Cursor, Codex) code in your cloud sandbox; Mythex provides the VM, preview, and publish.

The simple flow (recommended)

  1. Copy your MCP URL. It is in two places, whichever you reach first:

    • Account settings → MCP / Claude
    • Connectors (left sidebar) → Custom MCP, at the foot of the panel

    Production: https://mcp.mythex.ai/mcp

    The MCP URL under Connectors → Custom MCP

  2. In the client, add that URL as a custom MCP / connector

  3. Click Connect

  4. Your browser opens Mythex /mcp/consent — sign in if needed, then Allow access or Deny

  5. You’re done. Chat in Claude/Cursor and build

Anyone can Connect. Tool calls need a Mythex Pro account (and credits for sandbox time). Free can still Allow access; tools show an upgrade panel until the account is Pro.

Claude

Settings → Connectors → Add custom connector → paste MCP URL → Connect → approve on Mythex.

Cursor

Add the server with only the URL (Settings → MCP, or .cursor/mcp.json):

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

Toggle the server on → Connect when Cursor prompts → approve on Mythex.

Local dev can use http://localhost:4000/mcp the same way.

Requirements for tools

  • Pro plan (Connect works without it; tools return an upgrade error)
  • Credits on your balance (empty balance → sandbox wake refused / sandboxes pause)

What the client can do

  • Create / open projects and wake sandboxes
  • Read, write, edit, search files; run bash
  • Preview via set_run_config / start / logs
  • Env keys (set secrets you provide — values are not listed back)
  • Database, storage, publish, checkpoints
  • Browser run, web/media helpers, export/import, GitHub, domains

Tool results include a workspace_url (https://mythex.ai/p/{id}?from=mcp). Open it to watch the live preview and progress in Mythex while the client works in Cursor/Claude.

If you run out of credits (or need Pro), the tool returns an upgrade_url and Cursor shows a Mythex panel in chat (pricing / credits) — the same idea as inline image and video previews. Open the URL if you want checkout in the browser.

Preview tools (set_run_config, start_preview, get_preview) return preview_url for the in-chat live iframe. browser_run attaches Playwright screenshot() PNGs as images in chat (Claude/Cursor can display them).

What stays private

  • Mythex agent system prompts and internals
  • Platform secrets and other users’ projects
  • Raw secret values via list_env_keys (keys only)

Credits

  • The external model is billed by that provider (Claude / Cursor / etc.)
  • Mythex credits pay for live sandbox time and published hosting
  • Empty balance → sandbox wake refused / sandboxes pause

Related

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