agent-device

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snapshot

Capture the accessibility tree or compare it with the previous session baseline. Use the returned refs for subsequent semantic interactions and the diff option to verify UI changes. Times out after 90s; a caller-supplied budget extends it.

Instructions

Input Schema

Name	Required	Description
`raw`	No
`udid`	No	Apple device or simulator UDID; the selector that pins one device when several share a name.
`debug`	No	Enable debug diagnostics.
`depth`	No
`runId`	No	Lease run identifier.
`scope`	No
`device`	No	Device name selector (a UDID belongs in udid, a serial in serial).
`record`	No	Force-record this out-of-band observation into a repair-armed heal (mutually exclusive with noRecord). Authored replay steps are recorded automatically and never need this.
`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.
`noRecord`	No	Do not record this action.
`platform`	No	Platform selector used to resolve a device.
`forceFull`	No
`timeoutMs`	No	Maximum wall-clock time for the snapshot command.
`includeCost`	No	Include per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.
`observeOnly`	No	iOS only. Refuse instead of activating or repairing the session app. Reports XCUIApplication state, which does not prove screen ownership (#2696).
`deviceTarget`	No	Device target form. Maps to the CLI --target flag.
`customActions`	No	Name the affordances an element merged away (iOS UIAccessibilityCustomAction, React Native accessibilityActions) — a card whose reply/options controls are not separate elements still lists them here. The names are for PLANNING, not invocation: there is no API to trigger them, so reach the affordance through the element detail screen, through the same control exposed as a labeled element elsewhere, or by coordinates from its rect. iOS simulator only; costs one accessibility round trip per merged element.
`responseLevel`	No	Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
`interactiveOnly`	No
`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.

Changed1 schema field changedv0.21.27Oct 12, 2026

addedInput schema / properties / observeOnly

Added value: +{
+  "description": "iOS only. Refuse instead of activating or repairing the session app. Reports XCUIApplication state, which does not prove screen ownership (#2696).",
+  "type": "boolean"
+}

Changed3 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."

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"
-}

Changed1 schema field changedv0.20.9Aug 19, 2026

changedInput schema / properties / platform / enum

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

Changed1 schema field changedv0.20.6Aug 7, 2026

addedInput schema / properties / customActions

Added value: +{
+  "description": "Name the affordances an element merged away (iOS UIAccessibilityCustomAction, React Native accessibilityActions) — a card whose reply/options controls are not separate elements still lists them here. The names are for PLANNING, not invocation: there is no API to trigger them, so reach the affordance through the element detail screen, through the same control exposed as a labeled element elsewhere, or by coordinates from its rect. iOS simulator only; costs one accessibility round trip per merged element.",
+  "type": "boolean"
+}

Changed4 schema fields changedv0.20.2Jul 30, 2026

addedInput schema / properties / noRecord

Added value: +{
+  "description": "Do not record this action.",
+  "type": "boolean"
+}

changedInput schema / properties / platform / enum

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

addedInput schema / properties / record

Added value: +{
+  "description": "Force-record this out-of-band observation into a repair-armed heal (mutually exclusive with noRecord). Authored replay steps are recorded automatically and never need this.",
+  "type": "boolean"
+}

changedInput schema / properties / serial / description

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

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

removedInput schema / properties / compact

Removed value: -{
-  "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

B3.4/5.0

Behavior3/5

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

With no annotations, the description carries the full behavioral burden. It usefully discloses a 90s timeout and that a caller-supplied budget extends it, which is genuine behavioral context. However, it omits baseline/session prerequisites, permission or device-resolution requirements, and response shape for a 25-parameter tool.

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

Conciseness4/5

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

Three tight sentences with the core purpose front-loaded, followed by result-usage and the timeout caveat. Every sentence earns its place with no redundancy.

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

Completeness3/5

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

For a 25-parameter tool with no annotations and no output schema, the description covers the essential return semantics (refs) and the timeout, but leaves device-resolution and mode (record/noRecord/observeOnly) interactions unexplained. Adequate but with clear gaps.

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 high (~80%), so the schema already documents most parameters and a baseline of 3 is appropriate. The description adds only marginal meaning (the 'budget' tied to timeoutMs, and the 'diff option'); it does not clarify the many device-selector parameters beyond what the schema provides.

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

Purpose4/5

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

States a specific verb ("Capture") and resource ("accessibility tree"), plus the alternate dual mode (compare with previous session baseline). This clearly separates it from visual siblings like screenshot, though it doesn't explicitly name any sibling to contrast with.

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

Usage Guidelines3/5

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

Guidance is output-oriented rather than selection-oriented: it says to reuse the returned refs for 'subsequent semantic interactions' and to use the diff option to verify UI changes. There is no explicit when-to-use-vs-alternatives or when-not, so the usage is implied rather than stated.

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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Instructions

Input Schema

Schema Changelog

TDQS

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