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devices

List available devices and simulators for automation, using filters such as platform, device name, or UDID to select a target. Times out after 90 seconds.

Instructions

List available devices and simulators that can be selected for automation. Use platform, device, udid, or serial inputs on later commands to target one result. Times out after 90s.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
udidNoApple device or simulator UDID; the selector that pins one device when several share a name.
debugNoEnable debug diagnostics.
runIdNoLease run identifier.
deviceNoDevice name selector (a UDID belongs in udid, a serial in serial).
serialNoAndroid, HarmonyOS, or Vega VVD serial selector.
targetNoAlias for deviceTarget on commands without a UI target field. Interaction commands reserve target for the UI element.
tenantNoRemote tenant identifier.
leaseIdNoExisting lease identifier.
sessionNoAgent-device session name.
platformNoPlatform selector used to resolve a device.
includeCostNoInclude per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.
deviceTargetNoDevice target form. Maps to the CLI --target flag.
responseLevelNoResponse verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
mcpOutputFormatNoMCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.
androidDeviceAllowlistNoAndroid serial allowlist used for device resolution.

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
devicesYes

Schema Changelog

Changes observed during successful MCP inspections.

  1. Changed3 schema fields changedv0.21.0
    • 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."
  2. Changed8 schema fields changedv0.20.10
    • 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"
      -}
  3. Changed2 schema fields changedv0.20.9
    • changedInput schema / properties / platform / enum
      Previous value: -[
      -  "apple",
      -  "android",
      -  "vega",
      -  "linux",
      -  "web",
      -  "ios",
      -  "macos"
      -]New value: +[
      +  "apple",
      +  "android",
      +  "harmonyos",
      +  "vega",
      +  "linux",
      +  "web",
      +  "ios",
      +  "macos"
      +]
    • changedOutput schema / properties / devices / items / properties / platform / enum
      Previous value: -[
      -  "ios",
      -  "macos",
      -  "android",
      -  "vega",
      -  "linux",
      -  "web"
      -]New value: +[
      +  "ios",
      +  "macos",
      +  "android",
      +  "harmonyos",
      +  "vega",
      +  "linux",
      +  "web"
      +]
  4. Changed3 schema fields changedv0.20.2
    • 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."
    • changedOutput schema / (root)
      Previous value: -nullNew value: +{
      +  "properties": {
      +    "devices": {
      +      "items": {
      +        "properties": {
      +          "id": {
      +            "type": "string"
      +          },
      +          "kind": {
      +            "enum": [
      +              "simulator",
      +              "emulator",
      +              "device"
      +            ],
      +            "type": "string"
      +          },
      +          "name": {
      +            "type": "string"
      +          },
      +          "platform": {
      +            "enum": [
      +              "ios",
      +              "macos",
      +              "android",
      +              "vega",
      +              "linux",
      +              "web"
      +            ],
      +            "type": "string"
      +          },
      +          "target": {
      +            "enum": [
      +              "mobile",
      +              "tv",
      +              "desktop"
      +            ],
      +            "type": "string"
      +          }
      +        },
      +        "required": [
      +          "platform",
      +          "target",
      +          "kind",
      +          "id",
      +          "name"
      +        ],
      +        "type": "object"
      +      },
      +      "type": "array"
      +    }
      +  },
      +  "required": [
      +    "devices"
      +  ],
      +  "type": "object"
      +}
  5. Changed3 schema fields changedv0.17.11
    • 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"
      +}
  6. Changed1 schema field changedv0.17.7
    • changedInput schema / properties / platform / enum
      Previous value: -[
      -  "ios",
      -  "macos",
      -  "android",
      -  "linux",
      -  "apple"
      -]New value: +[
      +  "ios",
      +  "macos",
      +  "android",
      +  "linux",
      +  "web",
      +  "apple"
      +]
  7. Changed5 schema fields changedv0.17.6
    • 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"
      +]
  8. First observedv0.16.9

TDQS

A4/5.0
Behavior3/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It reveals a 90-second timeout, which is a concrete operational detail. However, it does not state whether the operation is read-only, whether it requires special permissions, or how it behaves on failure or partial results. The timeout is useful but the overall behavioral picture is incomplete.

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 waste. The purpose is stated first, followed by a practical usage hint and a timeout note. Every sentence earns its place, and the description is appropriately brief for a list tool.

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?

The tool has a rich output schema (true) and 15 optional parameters all documented in the schema, so the description need not explain return values. It covers the core purpose, the selector reuse pattern, and the timeout. For a discovery tool, this is sufficient; the only minor gap is that it doesn't explicitly mention that the filters are optional or that the output is a list, but these are implied by the verb 'List' and the schema.

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 description coverage is 100%, so each parameter is already documented in the input schema. The description mentions platform, device, udid, or serial as selectors, but this primarily guides usage of later commands, not the parameters of this tool itself. It adds little semantic meaning beyond what the schema provides, so the baseline 3 is appropriate.

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?

States the action 'List' and the resource 'available devices and simulators' explicitly, and clarifies the purpose 'can be selected for automation.' The verb is specific and distinguishes it from action-oriented siblings like boot, click, or install, which have clearly different purposes.

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?

Gives clear guidance on how to use the output: 'Use platform, device, udid, or serial inputs on later commands to target one result.' This explains the primary use case. However, it does not explicitly mention when not to use this tool or name alternative listing tools (e.g., get, find), though the siblings suggest those might serve other resources. The guidance is sufficient but not exhaustive.

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