get_booted_sim_id
Get the ID of the currently booted iOS simulator
LABSCO SUMMARY
The agent can see the screen it is tapping.
What it takes off you is the describe-then-guess loop. The accessibility tree returns the elements a tap is aimed at, so the coordinates come from the screen rather than from an assumption — and a screenshot or a recording is one call away when a run has to be shown rather than described.
What it is
A simulator control server built on Facebook's IDB. It finds the booted simulator, describes what is on screen through the accessibility tree, drives the UI by coordinate, and captures the run as a screenshot or a video.
What you get
- The booted simulator's id, and the Simulator application opened (
get_booted_sim_id,open_simulator) - The whole screen described through its accessibility tree, one point described, or elements found by search criteria and match mode (
ui_describe_all,ui_describe_point,ui_find_element,ui_view) - Taps, typing and swipes at coordinates, with duration control (
ui_tap,ui_type,ui_swipe) - A screenshot for the model to look at, and video recorded and stopped on demand (
screenshot,record_video,stop_recording) - Apps installed from a bundle, launched, terminated, and the installed ones listed (
install_app,launch_app,terminate_app,list_apps) - A URL opened on the simulator, which is how you deep-link straight to the screen under test (
open_url)
Requirements
macOS — iOS simulators exist nowhere else — with Xcode and its simulators installed, Node.js 20 or later, and Facebook's IDB tool. Every UI call takes a udid, which the booted-simulator call supplies. Three environment variables shape it: IOS_SIMULATOR_MCP_IDB_PATH when idb is not on the PATH, IOS_SIMULATOR_MCP_DEFAULT_OUTPUT_DIR for screenshots and recordings (~/Downloads otherwise, which matters when the agent's file access is restricted), and IOS_SIMULATOR_MCP_FILTERED_TOOLS to keep named tools out of the registered list entirely.
Setup effort
One command — npx -y ios-simulator-mcp
USE CASES
01
Walking a flow before you ship it
Describe the screen, act on what is actually there, and describe it again. Each step is checked against the accessibility tree rather than against a coordinate somebody wrote down last month.
02
Reproducing a bug on camera
Start recording, drive the steps, stop. What you attach to the ticket is the failure happening, not a description of it — and the output directory is configurable so the file lands where you can find it.
03
Checking a build installs and opens
Install the bundle, launch it by bundle id, and screenshot the first screen. That is the smoke test, and it takes three calls.
04
Deep-linking straight to the screen you care about
Open the URL on the simulator rather than tapping through five screens to reach the one under test. It cuts the setup out of every run.
05
Finding the control you meant
Search the tree by criteria instead of describing the whole screen and scanning it, or describe a single point when you want to know what is under a coordinate.
06
Keeping the tool list to what this agent should do
Filter out the tools you do not want registered — screen recording, for instance — with the filtered-tools variable. Removing them is more reliable than asking the model not to use them.
14 tools
Counted once with only startup setup. Other versions, modes or optional credentials may expose a different list.
install_app
Installs an app bundle (.app or .ipa) on the iOS Simulator
launch_app
Launches an app on the iOS Simulator by bundle identifier
open_simulator
Opens the iOS Simulator application
record_video
Records a video of the iOS Simulator using simctl directly
screenshot
Takes a screenshot of the iOS Simulator
stop_recording
Stops the simulator video recording using killall
ui_describe_all
Describes accessibility information for the entire screen in the iOS Simulator
ui_describe_point
Returns the accessibility element at given co-ordinates on the iOS Simulator's screen
ui_find_element
Searches the accessibility tree and returns elements matching the given criteria
ui_swipe
Swipe on the screen in the iOS Simulator
ui_tap
Tap on the screen in the iOS Simulator
ui_type
Input text into the iOS Simulator
ui_view
Get the image content of a compressed screenshot of the current simulator view
BEFORE YOU INSTALL
What to know first
Tools you get
14 tools when we connected. The documentation lists 17; terminate_app, open_url and list_apps read as recent additions and may be missing from an older published build. Deep-linking depends on open_url.
Requires
- Node.js 20 or later
- macOS (as iOS simulators are only available on macOS)
- Xcode and iOS simulators installed
- Facebook IDB tool (see install guide)
CONTEXT COST
Light Standing cost
Rated by the size of the 14 tool definitions that ride along on every turn, not by how many there are
INSTALLATION
Connect your client
Server setup
Build from source
Clone this repository
TERMINAL
git clone https://github.com/joshuayoes/ios-simulator-mcp
cd ios-simulator-mcpInstall dependencies (npm is the default; pnpm is also supported)
TERMINAL
npm installBuild the project
TERMINAL
npm run buildnpx
TERMINAL
npx -y ios-simulator-mcpMCP Clients
Cursor
CURSOR · JSON
{
"mcpServers": {
"ios-simulator": {
"command": "npx",
"args": [
"-y",
"ios-simulator-mcp"
]
}
}
}Claude Code
CLAUDE CODE · TERMINAL
claude mcp add ios-simulator npx ios-simulator-mcp
