iOS Simulator MCP: local or remote, and which to use
Disclosure: I make thumbs, one of the options below. I'll say where each option fits, including where mine doesn't.
An "iOS Simulator MCP" server gives an AI agent the controls of Apple's iOS Simulator: see the screen, tap, type, swipe, open a link, launch an app. Then Claude Code, Cursor or another MCP client can use an iPhone screen the way it uses a terminal. There are two kinds, and which one fits depends on whether you have a Mac and what you want to test.
What an iOS Simulator MCP server does
The Simulator is a copy of iOS that runs on a Mac. An MCP server wraps it so an agent can call tools instead of you clicking. The useful set is small: screenshot, read what's on screen (the accessibility tree: labels and positions of what can be tapped), tap, type, swipe, open a URL and launch an app. With those, an agent can look at a screen, decide, act and check the result.
Local servers
A local server runs on your Mac next to Xcode and drives the Simulator installed there. Two open-source examples:
- ios-simulator-mcp exposes tools such as screenshot, tap, type, swipe, describe the screen, open a URL, install and launch an app. Per its README it needs macOS, Xcode with simulators, Node.js and Facebook's IDB tool.
- XcodeBuildMCP (now maintained under Sentry's GitHub organisation) is aimed at building, running and testing iOS and macOS projects from an agent. It also needs macOS and Xcode.
Local is free, private and under your control, and it can run your own app: build it in Xcode, install it in the Simulator and let the agent walk it. The catch is setup: a Mac, Xcode, simulators, extra tools and a config file per client.
A remote server
A remote MCP server lives at a URL and uses OAuth sign-in, so there is nothing to install. The Simulator runs on the provider's side. thumbs works this way:
claude mcp add --transport http thumbs https://mcp.usethumbs.com/mcp
Then run /mcp in Claude Code and sign in with Google. No Mac, no Xcode, no cable. The trade-offs are real, though: thumbs' early access is shared between testers, has Safari and Apple's built-in apps only (not App Store apps, and not your own builds) and lets people in one at a time from a waitlist.
Which one to pick
| Local server (ios-simulator-mcp, XcodeBuildMCP) | Remote server (thumbs early access) | |
|---|---|---|
| Needs | A Mac with Xcode, simulators and extra tools | A URL and a Google sign-in |
| Your own app | Yes: build it and install it | No, not in early access |
| Your web app in Safari | Yes | Yes |
| Sharing | Yours alone | Shared between testers, in turns |
| Cost | Free, open source | Free in early access; own iPhone planned, no price yet |
If you have a Mac and want to test a native app you are building, a local server is the right tool today. If you have no Mac in the loop, or you just want an agent to open your site in Safari on an iPhone and tell you what it sees, the remote one is faster to start. They can live side by side in the same client.
Connect thumbs from Claude Code or Cursor
- Claude Code: the command above, then
/mcpto sign in. - Cursor: add this to
~/.cursor/mcp.json, then sign in when Cursor asks:{ "mcpServers": { "thumbs": { "url": "https://mcp.usethumbs.com/mcp" } } } - Claude app: add the same URL as a custom connector.
Only accounts let in from the waitlist can use a phone.
Limits
- thumbs' early access is the iOS Simulator, not a real iPhone. It is a good guide to layout and behaviour, with no real touch hardware, network or battery conditions. A real iPhone of your own is planned; it isn't available yet and has no date or price.
- Don't sign in to personal accounts on a shared Simulator.
- No banking apps, Apple Pay or anything behind Face ID.
FAQ
What is an iOS Simulator MCP server? An MCP server that exposes the iOS Simulator to an AI agent as tools: take a screenshot, read what is on screen, tap, type, swipe, open a link or launch an app.
Do I need a Mac? For a local iOS Simulator MCP server, yes: the Simulator only runs on macOS, with Xcode installed. With a remote server such as thumbs you add a URL and sign in, and the Simulator runs on our side.
Can I install my own app in thumbs' Simulator? No. Early access is shared between testers and has Safari and Apple's built-in apps, not App Store apps or your own builds. For your own app, use a local server today; a real iPhone of your own is planned, with no date or price.
Does it work with Claude Code and Cursor? Yes. Local and remote MCP servers both work with either. For thumbs: claude mcp add --transport http thumbs https://mcp.usethumbs.com/mcp in Claude Code, or add the URL to ~/.cursor/mcp.json in Cursor.
Is thumbs free? Early access is free, on the iOS Simulator, let in one at a time from a waitlist. The own-iPhone option isn't available yet and has no price.
Keep reading
- How to test an iOS app with Claude Code or Cursor: what works today for a native app and for a web app.
- How to give an AI agent an iPhone with MCP: how it works under the hood.
- How to test your web app on an iPhone with an AI agent.
- Remote vs local MCP servers: how OAuth sign-in works: what happens when you sign in to a remote server.
- Does the iOS keyboard cover your Submit button?: a web-app check you can run in early access.