agent-device

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back

Navigate back through the app's navigation stack or trigger the platform's back behavior on mobile, TV, or desktop devices. Use in-app mode for app navigation, system mode for OS-level back.

Instructions

Navigate back in the app or through system navigation. Use in-app for the app navigation stack and system when the platform back behavior is required. Times out after 90s; a caller-supplied budget extends it.

Input Schema

TableJSON Schema

Name	Required	Description
`mode`	No
`udid`	No	Apple device or simulator UDID; the selector that pins one device when several share a name.
`debug`	No	Enable debug diagnostics.
`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.
`settle`	No	After the action, wait for the UI to go quiet and return the settled diff vs the pre-action tree in the same response. Best-effort; never fails the action.
`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.
`timeoutMs`	No	Settle: wait deadline in milliseconds (default 10000).
`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.
`responseLevel`	No	Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
`settleQuietMs`	No	Settle: quiet window in milliseconds (default 500).
`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.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`mode`	Yes
`action`	Yes
`settle`	No
`message`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

Changed1 schema field changedv0.21.2Sep 16, 2026

addedOutput schema / properties / settle / properties / surfaceChange

Added value: +{
+  "description": "Present when an in-place system surface (web sign-in or Apple Pay sheet) was presented over the app, or left it.",
+  "properties": {
+    "disclosure": {
+      "description": "Agent-facing sentence explaining the surface transition.",
+      "type": "string"
+    },
+    "from": {
+      "description": "Surface the pre-action baseline described: a host bundle id, or app.",
+      "type": "string"
+    },
+    "to": {
+      "description": "Surface the post-action capture describes: a host bundle id, or app.",
+      "type": "string"
+    }
+  },
+  "required": [
+    "from",
+    "to",
+    "disclosure"
+  ],
+  "type": "object"
+}

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"
+]

Changed4 schema fields changedv0.20.6Aug 7, 2026

addedInput schema / properties / settle

Added value: +{
+  "description": "After the action, wait for the UI to go quiet and return the settled diff vs the pre-action tree in the same response. Best-effort; never fails the action.",
+  "type": "boolean"
+}

addedInput schema / properties / settleQuietMs

Added value: +{
+  "description": "Settle: quiet window in milliseconds (default 500).",
+  "minimum": 0,
+  "type": "integer"
+}

addedInput schema / properties / timeoutMs

Added value: +{
+  "description": "Settle: wait deadline in milliseconds (default 10000).",
+  "minimum": 1,
+  "type": "integer"
+}

addedOutput schema / properties / settle

Added value: +{
+  "properties": {
+    "captures": {
+      "type": "number"
+    },
+    "diff": {
+      "description": "Settled diff vs the pre-action tree (changed lines only).",
+      "properties": {
+        "lines": {
+          "items": {
+            "properties": {
+              "kind": {
+                "enum": [
+                  "added",
+                  "removed"
+                ],
+                "type": "string"
+              },
+              "ref": {
+                "description": "Plain ref body (e12) for added lines.",
+                "type": "string"
+              },
+              "text": {
+                "type": "string"
+              }
+            },
+            "required": [
+              "kind",
+              "text"
+            ],
+            "type": "object"
+          },
+          "type": "array"
+        },
+        "summary": {
+          "properties": {
+            "additions": {
+              "type": "number"
+            },
+            "removals": {
+              "type": "number"
+            },
+            "unchanged": {
+              "type": "number"
+            }
+          },
+          "required": [
+            "additions",
+            "removals",
+            "unchanged"
+          ],
+          "type": "object"
+        },
+        "truncated": {
+          "description": "Lines were capped to the response bound.",
+          "type": "boolean"
+        }
+      },
+      "required": [
+        "summary",
+        "lines"
+      ],
+      "type": "object"
+    },
+    "hint": {
+      "type": "string"
+    },
+    "quietMs": {
+      "type": "number"
+    },
+    "refs": {
+      "items": {
+        "properties": {
+          "ref": {
+            "description": "Plain ref body (e12) minted from the stored settled tree.",
+            "type": "string"
+          }
+        },
+        "required": [
+          "ref"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "refsGeneration": {
+      "description": "Snapshot generation of the stored settled tree; refs on added diff lines were minted from it.",
+      "type": "number"
+    },
+    "settled": {
+      "description": "Whether the UI held the quiet window before the deadline. false is advisory, not failure.",
+      "type": "boolean"
+    },
+    "tail": {
+      "description": "Unchanged interactive refs tail: still-present, actionable elements from the settled tree, attached only when diff carries zero added-line refs (a modal-dismiss/toast-only diff).",
+      "items": {
+        "properties": {
+          "label": {
+            "type": "string"
+          },
+          "ref": {
+            "description": "Plain ref body (e12) minted from the stored settled tree.",
+            "type": "string"
+          },
+          "role": {
+            "type": "string"
+          }
+        },
+        "required": [
+          "ref",
+          "role"
+        ],
+        "type": "object"
+      },
+      "type": "array"
+    },
+    "tailTruncated": {
+      "description": "Present (true) when tail candidates exceeded the response cap.",
+      "type": "boolean"
+    },
+    "timeoutMs": {
+      "type": "number"
+    },
+    "waitedMs": {
+      "type": "number"
+    }
+  },
+  "required": [
+    "settled",
+    "waitedMs",
+    "captures",
+    "quietMs",
+    "timeoutMs"
+  ],
+  "type": "object"
+}

Changed3 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"
+]

changedInput schema / properties / serial / description

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

Changed4 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"
+}

changedOutput schema / (root)

Previous value: -nullNew value: +{
+  "properties": {
+    "action": {
+      "const": "back",
+      "type": "string"
+    },
+    "message": {
+      "type": "string"
+    },
+    "mode": {
+      "enum": [
+        "in-app",
+        "system"
+      ],
+      "type": "string"
+    }
+  },
+  "required": [
+    "action",
+    "mode",
+    "message"
+  ],
+  "type": "object"
+}

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"
+]

Changed5 schema fields changedv0.17.6Jun 18, 2026

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

A3.9/5.0

Behavior3/5

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

No annotations are provided, so the description carries the full behavioral disclosure burden. It mentions timeout (90s) and budget extension, and the settle behavior is described as best-effort. However, it does not disclose what happens on navigation failure, whether the action is reversible, or any side effects. For a navigation tool, this is adequate but not comprehensive.

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?

Two sentences with zero fluff. The first sentence states the purpose and modes, the second adds usage and timeout behavior. Information is front-loaded and every clause earns its place. Ideal conciseness.

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?

Given the tool has 20 parameters but 95% schema coverage and an output schema, the description covers the essential behavioral aspects: the two modes, timeout, and settle behavior. It doesn't explain return values (output schema handles that) or list all parameters (schema does). It is complete for an agent to call it correctly, though it could briefly mention what happens when no mode is specified (defaults are not stated).

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 description coverage is 95%, so most parameters are already documented. The description adds meaningful context for the 'mode' parameter (in-app vs system) and clarifies the settle option ('wait for the UI to go quiet and return the settled diff'). This goes beyond the schema and helps the agent understand parameter purpose and interaction.

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?

The description clearly states the tool's function: navigating back in-app or through system navigation. It names the resource (navigation) and the two modes (in-app vs system), which distinguishes the two distinct behaviors. However, it does not explicitly differentiate from sibling navigation tools like app-switcher or home, though the context is clear.

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 provides explicit guidance on when to use each mode: 'Use in-app for the app navigation stack and system when the platform back behavior is required.' This is actionable and clarifies the primary decision. It does not mention alternatives or exclusion cases, but the mode selection is well-covered.

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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Input Schema

Output Schema

Schema Changelog

TDQS

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