agent-device

Official

Overview Schema Related Servers Score Discussions

viewport

Resize the active web viewport before taking snapshots or screenshots. Useful for revealing different content in fixed-layout or 100vh apps.

Instructions

Resize the active web viewport before taking snapshots or screenshots. Useful for fixed-layout or 100vh apps where changing the viewport reveals different content.

Input Schema

TableJSON Schema

Name	Required	Description
`cwd`	No	Working directory for command execution.
`udid`	No	iOS device UDID selector.
`debug`	No	Enable debug diagnostics.
`runId`	No	Lease run identifier.
`width`	Yes	Viewport width in CSS pixels.
`device`	No	Device name selector.
`height`	Yes	Viewport height in CSS pixels.
`serial`	No	Android device 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.
`stateDir`	No	Agent-device state directory.
`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.
`daemonBaseUrl`	No	Remote daemon base URL.
`responseLevel`	No	Response verbosity: token-cheap digest / default (today) / full. Defaults to default; the default response shape is unchanged.
`daemonAuthToken`	No	Remote daemon auth token.
`iosXctestEnvDir`	No	Writable directory for iOS XCTest runner env overlays.
`mcpOutputFormat`	No	MCP text content format. Defaults to optimized agent-friendly text; use json for JSON text. Structured content is always returned separately.
`iosXctestrunFile`	No	Externally built iOS XCTest runner .xctestrun artifact path.
`iosSimulatorDeviceSet`	No	iOS simulator device-set path used for device resolution.
`androidDeviceAllowlist`	No	Android serial allowlist used for device resolution.
`iosXctestDerivedDataPath`	No	Derived data path for external iOS XCTest runner execution.

Output Schema

TableJSON Schema

Name	Required	Description	Default
`width`	Yes
`height`	Yes
`message`	Yes

Tool Definition Quality

A4/5.0

Behavior3/5

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

No annotations are available, so the description carries the burden. It explains the resize operation and its purpose, but does not disclose whether the viewport change is persistent, whether it triggers a reload, or other side effects. Moderate transparency.

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 that front-load the action and then give the use case. Every sentence contributes value; no wasted words.

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 rich input schema, output schema, and relatively simple operation, the description covers the core action and use case sufficiently. It could mention side effects (persistence, reload), but the essential information for selecting and invoking is present.

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%, with parameters like 'Viewport width in CSS pixels' already well documented. The description adds only contextual framing ('changing the viewport reveals different content') and does not materially extend parameter semantics beyond the schema.

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 clearly states 'Resize the active web viewport before taking snapshots or screenshots' – a specific verb and resource. It differentiates from sibling tools like screenshot/snapshot by focusing on the viewport resizing action as a preparatory step.

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?

Provides clear context: use this when preparing for snapshots/screenshots, especially for fixed-layout or 100vh apps. It does not explicitly name alternatives or exclusion criteria, but the intended use case is well-scoped.

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

Install Server

Other Tools

Latest Blog Posts

Who's Calling? MCP Hosts Are an Identity Blind Spot (And the Spec Knows It)
By Om-Shree-0709 on July 25, 2026.
mcp
Agent Identity
OAuth 2.1
Your AI Chatbot Just Exposed Your CEO's Salary to an Intern
By Om-Shree-0709 on July 2, 2026.
Agent Identity
MCP Security
OAuth Delegation
Why MCP Servers Need Execution Sandboxing (And Why Your Current Stack Isn't Enough)
By Om-Shree-0709 on June 30, 2026.
Agentic Ai
Prompt Injection
WebAssembly

MCP directory API

We provide all the information about MCP servers via our MCP API.

curl -X GET 'https://glama.ai/api/mcp/v1/servers/callstack/agent-device'

If you have feedback or need assistance with the MCP directory API, please join our Discord server