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launch_app

Launch an installed app on a specific simulator using its bundle ID and simulator UDID. Optionally provide launch arguments or wait for a debugger.

Instructions

Launch an installed app on a simulator

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "udid": "<udid>",
      "bundleId": "<bundleId>"
    },
    "name": "launch_app"
  }
}

Input Schema

Name	Required	Description
`args`	No	Arguments to pass to the app on launch
`udid`	Yes	The UDID of the simulator
`bundleId`	Yes	Bundle identifier of the app to launch
`waitForDebugger`	No	Wait for a debugger to attach before starting the app

Schema Changelog

Changes observed during successful MCP inspections.

First observedv1.0.3Aug 8, 2026

TDQS

B3.2/5.0

Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full burden of behavioral disclosure. It only states the core action ('Launch') without revealing what happens if the app is not installed, whether the tool is blocking, or if any side effects occur. No additional behavioral context is given.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single, front-loaded sentence with zero wasted wording. It is exactly as concise as possible while still stating the primary purpose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness2/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool has no annotations, no output schema, and a very terse description, the context is sparse. The description omits important conditions such as requiring the app to be installed and simulator to be booted, and gives no hints about failure modes or expected outcomes. This is insufficient for an agent to use the tool safely in a workflow.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100% for all four parameters, so the baseline is 3. The description adds no information beyond the schema; it does not even mention parameters such as udid or bundleId, but the schema already provides clear per-parameter descriptions.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description uses a specific verb ('Launch') and identifies the resource ('installed app on a simulator'). It clearly distinguishes the tool from siblings like install_app, terminate_app, or open_url by stating exactly what action it performs.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

No guidance is provided on when to use this tool versus alternatives such as install_app or boot_simulator. The description offers no context about prerequisite conditions (e.g., app already installed, simulator booted) or exclusions.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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