mobilerun-mcp

Get Ui Tree

get_ui_tree

Retrieves a compact accessibility tree from a device screen, including element class, ID, label, and bounds, to support screen reading for automation.

Instructions

Compact accessibility tree (class, id, label, flags C/L/E/S/K/P, bounds).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "get_ui_tree"
  }
}

Input Schema

Name	Required	Description	Default
`device`	No
`max_depth`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 27, 2026

TDQS

C2.6/5.0

Behavior2/5

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

With no annotations, the description carries the full burden. It adds that the tree is 'compact' and lists output fields, but does not disclose how accessibility data is obtained, what happens when the tree is unavailable, whether permissions are needed, or how max_depth affects results. These are significant behavioral gaps.

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

Conciseness4/5

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

The description is a single dense sentence with no filler and the key output concept is front-loaded. The field list is compact and informative, though the brevity comes at the cost of missing guidance.

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

Completeness2/5

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

The output schema covers return structure, so explaining field contents is less critical. However, with zero annotations and zero parameter documentation, the description is too sparse to fully support correct invocation; it lacks device handling, depth semantics, and sibling differentiation.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters1/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so the description must compensate for the undocumented device and max_depth parameters. It does not mention either parameter, leaving an agent unable to infer device selection or depth behavior from the description.

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

Purpose4/5

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

The description identifies the resource (accessibility tree) and specifies the exact contents: class, id, label, flags, and bounds. It is not a tautology, but it does not differentiate from sibling tools like read_screen or perceive_screen.

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 given on when to use this tool versus alternatives such as get_screenshot, read_screen, or perceive_screen. The description provides no context about suitable scenarios or exclusions.

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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