Skip to main content

​
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.
  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):
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