agent-device

Official

by callstack

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TypeScript

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Boots the selected device when needed and opens an app, deep link, or URL to act as the foreground automation target.

Instructions

Boot the selected device when needed, then open an app, deep link, or URL in a session. Use the app or URL inputs to choose what becomes the foreground automation target. Metro and debug runtime hints given here are recorded as the session's dev-server binding, so a later reload reuses them; a fresh open without them clears any binding left by a previous same-name session. Times out after 90s; a caller-supplied budget extends it.

Input Schema

TableJSON Schema

Name	Required	Description
`app`	No	App name, bundle id, package, or URL.
`url`	No	Optional URL passed with an app shell.
`udid`	No	Apple device or simulator UDID; the selector that pins one device when several share a name.
`debug`	No	Enable debug diagnostics.
`force`	No	Overwrite an existing --save-script target instead of refusing (alias: --overwrite).
`runId`	No	Lease run identifier.
`device`	No	Device name selector (a UDID belongs in udid, a serial in serial).
`serial`	No	Android, HarmonyOS, or Vega VVD serial selector.
`target`	No	Alias for deviceTarget on commands without a UI target field. Interaction commands reserve target for the UI element.
`tenant`	No	Remote tenant identifier.
`leaseId`	No	Existing lease identifier.
`session`	No	Agent-device session name.
`surface`	No	macOS presentation surface to open: the app itself, the frontmost app, the desktop, or the menu bar.
`testIme`	No	Activate the headless Android test IME for deterministic Unicode text entry (default on for emulators; opt-in on real devices).
`activity`	No	Android activity name.
`noRecord`	No	Do not record this action.
`platform`	No	Platform selector used to resolve a device.
`relaunch`	No	Force relaunch.
`bundleUrl`	No	Session-scoped bundle URL hint applied to the opened app.
`deviceHub`	No	Use Xcode Device Hub when surfacing Apple simulators.
`launchUrl`	No	Session-scoped launch URL hint applied to the opened app.
`metroHost`	No	Session-scoped Metro/debug host hint applied to the opened app.
`metroPort`	No	Session-scoped Metro/debug port hint applied to the opened app. On an emulator/simulator the host defaults to the loopback alias (Android 10.0.2.2, iOS 127.0.0.1) when --metro-host is omitted; physical devices still require an explicit --metro-host.
`timeoutMs`	No	Startup budget in milliseconds. Bounds the Simulator boot wait, so a never-booted Simulator can finish its first-boot migration; omit for the default startup behavior.
`foreground`	No	Include an initial interactive snapshot in a fresh open response. With no app argument, discover the sole running app on the sole booted iOS simulator; ambiguous environments fail closed.
`launchArgs`	No	Launch arguments forwarded verbatim to the platform launch command.
`saveScript`	No
`includeCost`	No	Include per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.
`deviceTarget`	No	Device target form. Maps to the CLI --target flag.
`launchConsole`	No	Launch console mode.
`responseLevel`	No	Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
`mcpOutputFormat`	No	MCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.
`androidDeviceAllowlist`	No	Android serial allowlist used for device resolution.

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv0.21.0Sep 9, 2026

changedInput schema / properties / device / description

Previous value: -"Device name selector."New value: +"Device name selector (a UDID belongs in udid, a serial in serial)."

changedInput schema / properties / serial / description

Previous value: -"Android device or Vega VVD serial selector."New value: +"Android, HarmonyOS, or Vega VVD serial selector."

addedInput schema / properties / timeoutMs

Added value: +{
+  "description": "Startup budget in milliseconds. Bounds the Simulator boot wait, so a never-booted Simulator can finish its first-boot migration; omit for the default startup behavior.",
+  "minimum": 1,
+  "type": "integer"
+}

changedInput schema / properties / udid / description

Previous value: -"iOS device UDID selector."New value: +"Apple device or simulator UDID; the selector that pins one device when several share a name."

Changed8 schema fields changedv0.20.10Aug 26, 2026

removedInput schema / properties / cwd

Removed value: -{
-  "description": "Working directory for command execution.",
-  "type": "string"
-}

removedInput schema / properties / daemonAuthToken

Removed value: -{
-  "description": "Remote daemon auth token.",
-  "type": "string"
-}

removedInput schema / properties / daemonBaseUrl

Removed value: -{
-  "description": "Remote daemon base URL.",
-  "type": "string"
-}

removedInput schema / properties / iosSimulatorDeviceSet

Removed value: -{
-  "description": "iOS simulator device-set path used for device resolution.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestDerivedDataPath

Removed value: -{
-  "description": "Derived data path for external iOS XCTest runner execution.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestEnvDir

Removed value: -{
-  "description": "Writable directory for iOS XCTest runner env overlays.",
-  "type": "string"
-}

removedInput schema / properties / iosXctestrunFile

Removed value: -{
-  "description": "Externally built iOS XCTest runner .xctestrun artifact path.",
-  "type": "string"
-}

removedInput schema / properties / stateDir

Removed value: -{
-  "description": "Agent-device state directory.",
-  "type": "string"
-}

Changed2 schema fields changedv0.20.9Aug 19, 2026

changedInput schema / properties / foreground / description

Previous value: -"[RFC prototype] On a fresh session with no app argument, resolve the target from the sole booted iOS simulator's sole running app and include an initial interactive snapshot in the response. Fails with AMBIGUOUS_MATCH when the environment is not unambiguous (0 or 2+ booted simulators, or no confidently-detectable running app) — never guesses."New value: +"Include an initial interactive snapshot in a fresh open response. With no app argument, discover the sole running app on the sole booted iOS simulator; ambiguous environments fail closed."

changedInput schema / properties / platform / enum

Previous value: -[
-  "apple",
-  "android",
-  "vega",
-  "linux",
-  "web",
-  "ios",
-  "macos"
-]New value: +[
+  "apple",
+  "android",
+  "harmonyos",
+  "vega",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

Changed2 schema fields changedv0.20.6Aug 7, 2026

addedInput schema / properties / foreground

Added value: +{
+  "description": "[RFC prototype] On a fresh session with no app argument, resolve the target from the sole booted iOS simulator's sole running app and include an initial interactive snapshot in the response. Fails with AMBIGUOUS_MATCH when the environment is not unambiguous (0 or 2+ booted simulators, or no confidently-detectable running app) — never guesses.",
+  "type": "boolean"
+}

addedInput schema / properties / surface / description

Added value: +"macOS presentation surface to open: the app itself, the frontmost app, the desktop, or the menu bar."

Changed8 schema fields changedv0.20.2Jul 30, 2026

addedInput schema / properties / bundleUrl

Added value: +{
+  "description": "Session-scoped bundle URL hint applied to the opened app.",
+  "type": "string"
+}

addedInput schema / properties / force

Added value: +{
+  "description": "Overwrite an existing --save-script target instead of refusing (alias: --overwrite).",
+  "type": "boolean"
+}

addedInput schema / properties / launchUrl

Added value: +{
+  "description": "Session-scoped launch URL hint applied to the opened app.",
+  "type": "string"
+}

addedInput schema / properties / metroHost

Added value: +{
+  "description": "Session-scoped Metro/debug host hint applied to the opened app.",
+  "type": "string"
+}

addedInput schema / properties / metroPort

Added value: +{
+  "description": "Session-scoped Metro/debug port hint applied to the opened app. On an emulator/simulator the host defaults to the loopback alias (Android 10.0.2.2, iOS 127.0.0.1) when --metro-host is omitted; physical devices still require an explicit --metro-host.",
+  "maximum": 65535,
+  "minimum": 1,
+  "type": "integer"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "apple",
-  "android",
-  "linux",
-  "web",
-  "ios",
-  "macos"
-]New value: +[
+  "apple",
+  "android",
+  "vega",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

changedInput schema / properties / serial / description

Previous value: -"Android serial selector."New value: +"Android device or Vega VVD serial selector."

addedInput schema / properties / testIme

Added value: +{
+  "description": "Activate the headless Android test IME for deterministic Unicode text entry (default on for emulators; opt-in on real devices).",
+  "type": "boolean"
+}

Changed3 schema fields changedv0.17.11Jul 6, 2026

addedInput schema / properties / includeCost

Added value: +{
+  "description": "Include per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.",
+  "type": "boolean"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "macos",
-  "android",
-  "linux",
-  "web",
-  "apple"
-]New value: +[
+  "apple",
+  "android",
+  "linux",
+  "web",
+  "ios",
+  "macos"
+]

addedInput schema / properties / responseLevel

Added value: +{
+  "description": "Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.",
+  "enum": [
+    "digest",
+    "default",
+    "full"
+  ],
+  "type": "string"
+}

Changed1 schema field changedv0.17.7Jun 23, 2026

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "macos",
-  "android",
-  "linux",
-  "apple"
-]New value: +[
+  "ios",
+  "macos",
+  "android",
+  "linux",
+  "web",
+  "apple"
+]

Changed6 schema fields changedv0.17.6Jun 18, 2026

addedInput schema / properties / deviceHub

Added value: +{
+  "description": "Use Xcode Device Hub when surfacing Apple simulators.",
+  "type": "boolean"
+}

addedInput schema / properties / iosXctestDerivedDataPath

Added value: +{
+  "description": "Derived data path for external iOS XCTest runner execution.",
+  "type": "string"
+}

addedInput schema / properties / iosXctestEnvDir

Added value: +{
+  "description": "Writable directory for iOS XCTest runner env overlays.",
+  "type": "string"
+}

addedInput schema / properties / iosXctestrunFile

Added value: +{
+  "description": "Externally built iOS XCTest runner .xctestrun artifact path.",
+  "type": "string"
+}

addedInput schema / properties / mcpOutputFormat

Added value: +{
+  "description": "MCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.",
+  "enum": [
+    "optimized",
+    "json"
+  ],
+  "type": "string"
+}

changedInput schema / properties / platform / enum

Previous value: -[
-  "ios",
-  "android",
-  "macos",
-  "linux",
-  "apple"
-]New value: +[
+  "ios",
+  "macos",
+  "android",
+  "linux",
+  "apple"
+]

First observedv0.16.9Jun 3, 2026

TDQS

A4.4/5.0

Behavior4/5

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

With no annotations, the description carries the transparency burden and does disclose meaningful behavior: it may boot the device, it records Metro/debug hints as a session dev-server binding, a fresh open without those hints clears a previous same-name session binding, and it times out after 90 seconds unless a caller-supplied budget extends it. This goes well beyond restating the tool's function, though it does not cover all possible side effects or failure modes.

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 three sentences with no filler. The main action is front-loaded, followed by the session-binding behavior and timeout rule, and every sentence contributes information the schema does not already provide.

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

Completeness4/5

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

For a tool with 33 parameters and no output schema or annotations, the description covers the essential top-level workflow, the most surprising stateful behavior (binding persistence/clearing), and the timeout boundary. It does not describe response details or the many device-selector interactions, but the parameter schema already documents those in depth, so this is a reasonably complete high-level context.

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

Parameters4/5

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

Schema coverage is 97%, so the baseline is 3, and the description adds extra meaning by linking the app/url inputs to the foreground target concept, explaining that Metro/debug hints become session bindings, and noting that timeoutMs is a caller-supplied budget. This supplements the schema without duplicating it.

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 names a specific verb and resource: boot the selected device when needed, then open an app, deep link, or URL in a session. It also clarifies the intended outcome (making something the foreground automation target), which separates it from siblings like boot, install, and snapshot.

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

Usage Guidelines4/5

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

It gives clear context: use this tool to open an app, deep link, or URL and choose a foreground target, and it notes that device booting happens as needed. It does not explicitly name alternative tools or state when not to use it, but the intended scenario is unmistakable.

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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Schema Changelog

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