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screenshot

Capture a device screen image. Supports iOS, Android, desktop, and TV platforms with configurable output path and device selection.

Instructions

Capture a screenshot.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
cwdNoWorking directory for command execution.
pathNoOutput path.
udidNoiOS device UDID selector.
debugNoEnable debug diagnostics.
runIdNoLease run identifier.
deviceNoDevice name selector.
serialNoAndroid 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.
maxSizeNo
sessionNoAgent-device session name.
surfaceNo
platformNoPlatform selector used to resolve a device.
stateDirNoAgent-device state directory.
stabilizeNo
fullscreenNo
includeCostNoInclude per-command agent-cost (cost.wallClockMs, …) in structuredContent. Defaults to off; the default response shape is unchanged.
overlayRefsNo
deviceTargetNoDevice target form. Maps to the CLI --target flag.
daemonBaseUrlNoRemote daemon base URL.
responseLevelNoResponse verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
daemonAuthTokenNoRemote daemon auth token.
iosXctestEnvDirNoWritable directory for iOS XCTest runner env overlays.
mcpOutputFormatNoMCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.
iosXctestrunFileNoExternally built iOS XCTest runner .xctestrun artifact path.
normalizeStatusBarNo
iosSimulatorDeviceSetNoiOS simulator device-set path used for device resolution.
androidDeviceAllowlistNoAndroid serial allowlist used for device resolution.
iosXctestDerivedDataPathNoDerived data path for external iOS XCTest runner execution.
Behavior1/5

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

The description lacks any behavioral details beyond the basic action. It does not mention that it captures a device screen, where the image is saved, what format it uses, or any side effects. With no annotations, the description carries full burden but fails to disclose any behavioral traits.

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

Conciseness2/5

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

The description is a single sentence that is too terse for the complexity of the tool. It lacks structure and fails to convey important information, making it under-specified rather than concise.

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

Completeness1/5

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

With 30 parameters, no output schema, and no annotations, the description is severely incomplete. It does not explain what the screenshot captures (e.g., full screen, active window), how to interpret the output, or provide any operational context.

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 80%, so the schema already documents most parameter meanings. The tool description adds no parameter context beyond the schema, so baseline score of 3 is appropriate.

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

Purpose3/5

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

The description 'Capture a screenshot.' clearly indicates the action of taking a screenshot, but it is too generic and does not distinguish from sibling tools like 'snapshot' or 'record' that may also capture screen content.

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 vs alternatives, such as for capturing a static image versus recording video or taking a snapshot of UI structure.

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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