mcp-android-emulator

pinch_zoom

Simulate a pinch-zoom gesture on an Android device or emulator. Specify the center coordinates and scale factor to zoom in or out, with an optional duration.

Instructions

Perform a pinch zoom gesture (requires Android 8+)

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "x": "<x>",
      "y": "<y>",
      "scale": "<scale>"
    },
    "name": "pinch_zoom"
  }
}

Input Schema

Name	Required	Description
`x`	Yes	Center X coordinate
`y`	Yes	Center Y coordinate
`scale`	Yes	Scale factor (>1 zoom in, <1 zoom out)
`duration`	No	Duration in milliseconds (default: 500)

Schema Changelog

Changes observed during successful MCP inspections.

First observedv2.0.0Aug 2, 2026

TDQS

A3.7/5.0

Behavior2/5

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

No annotations are provided, so the description must carry the full behavioral burden. It notes the Android 8+ requirement but does not disclose other behavioral traits such as how the gesture is performed (e.g., whether it uses two fingers, whether it requires a stable UI, or how scale relates to screen coordinates). This is a minimal disclosure for a gesture tool.

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?

The description is a single, efficient sentence that states the action and a key prerequisite. No wasted words; it is appropriately minimal for a tool whose parameters are fully described in the schema.

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?

For a simple gesture tool with a fully self-describing schema, the description is minimally sufficient. However, it lacks context about return values (though no output schema is provided) and does not mention how this tool relates to other gestures or when the Android version matters. It is adequate but not rich.

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 100%, so the schema already documents all parameters including center coordinates, scale factor, and duration. The description adds no extra meaning, but the schema fully compensates, and the baseline for high coverage is 3; a small bonus is given because the scale parameter's semantics (>1 zoom in, <1 zoom out) are explicitly clear in 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 states a specific verb ('Perform') and resource ('pinch zoom gesture'), clearly distinguishing it from sibling gesture tools like swipe, drag, and double_tap. The Android 8+ requirement adds a useful constraint without ambiguity.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage as a gesture tool but does not explicitly state when to use pinch zoom versus alternatives (e.g., zoom via buttons or double_tap). The Android version requirement is a form of prerequisite guidance, but no explicit context or exclusions are given.

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