Mobile Next MCP

Get Screen Size

mobile_get_screen_size

Read-only

Retrieve the screen dimensions in pixels for a specified mobile device, enabling accurate UI testing and automation by providing essential display information.

Instructions

Get the screen size of the mobile device in pixels

Input Schema

TableJSON Schema

Name	Required	Description	Default
`device`	Yes	The device identifier to use. Use mobile_list_available_devices to find which devices are available to you.

Implementation Reference

src/server.ts:250-261 (handler)

The handler function for the 'mobile_get_screen_size' tool. It requires an active robot (device), calls getScreenSize() on it, and formats the response with width x height.

tool(
	"mobile_get_screen_size",
	"Get the screen size of the mobile device in pixels",
	{
		noParams
	},
	async ({}) => {
		requireRobot();
		const screenSize = await robot!.getScreenSize();
		return `Screen size is ${screenSize.width}x${screenSize.height} pixels`;
	}
);

src/server.ts:250-261 (registration)

Registers the 'mobile_get_screen_size' tool with the MCP server using the wrapper 'tool' function, including schema (noParams), description, and handler.

tool(
	"mobile_get_screen_size",
	"Get the screen size of the mobile device in pixels",
	{
		noParams
	},
	async ({}) => {
		requireRobot();
		const screenSize = await robot!.getScreenSize();
		return `Screen size is ${screenSize.width}x${screenSize.height} pixels`;
	}
);

src/server.ts:50-50 (schema)
Shared empty schema object used for tools with no parameters, including mobile_get_screen_size.
```
const noParams = z.object({});
```

Schema Changelog

Changes observed during successful MCP inspections.

Changed4 schema fields changedv1.0.0Jan 3, 2026

removedInput schema / additionalProperties
```
Removed value: -false
```

addedInput schema / properties / device

Added value: +{
+  "description": "The device identifier to use. Use mobile_list_available_devices to find which devices are available to you.",
+  "type": "string"
+}

removedInput schema / properties / noParams

Removed value: -{
-  "additionalProperties": false,
-  "properties": {},
-  "type": "object"
-}

changedInput schema / required

Previous value: -[
-  "noParams"
-]New value: +[
+  "device"
+]

First observedAug 15, 2025

TDQS

A3.5/5.0

Behavior3/5

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

The annotation readOnlyHint=true already signals a safe read operation, and the description's 'Get' is consistent with that. The description adds minor value by specifying the unit 'pixels' and the device scope, but does not disclose the return format or any other behavioral details.

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?

A single, clear sentence delivers the essential information with no filler. The action and subject are front-loaded, making it immediately scannable.

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?

The tool is simple, but since there is no output schema, the description leaves ambiguity about the exact return structure (e.g., width x height vs. diagonal). The phrase 'in pixels' offers the unit but not the shape of the result, which is a notable gap.

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?

The input schema fully documents the single 'device' parameter, including guidance to use mobile_list_available_devices. The description itself does not add parameter semantics beyond the schema, so the baseline score of 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?

The description clearly states the verb 'Get' and the resource 'screen size' with an explicit unit ('in pixels'). This sufficiently distinguishes it from sibling tools like mobile_get_orientation, which retrieves a different device property.

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?

The description provides no guidance on when to use this tool versus alternatives. The only contextual hint appears in the schema's parameter description (referencing mobile_list_available_devices), which helps with parameter selection but not tool selection.

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