mobilerun-mcp

Start App

start_app

Launches an app on a mobile device by its Android package or iOS bundle ID, optionally targeting a specific activity.

Instructions

Start an app by id (Android package / iOS bundle id), optionally a specific activity.

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": "start_app"
  }
}

Input Schema

Name	Required	Description	Default
`app_id`	No
`device`	No
`package`	No
`activity`	No

Output Schema

Name	Required	Description	Default
No arguments

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Sep 27, 2026

TDQS

C2.7/5.0

Behavior2/5

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

With no annotations, the description carries the full behavioral burden. It does not state whether the call blocks until the app is foregrounded, what happens if the app is not installed, whether it requires a connected device, or how the device parameter interacts with the operation. Only the minimal 'start an app' semantics are disclosed.

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?

A single front-loaded sentence with no filler; the core verb and resource lead. It is efficient but borders on under-specification given the tool's four parameters and unclear sibling overlap.

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?

An output schema exists so return values need not be explained. However, for a 4-parameter tool with zero schema coverage, no annotations, and a near-duplicate sibling in launch_app, the description omits the device/package semantics and any disambiguation, leaving real gaps an agent must fill by guessing.

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

Parameters2/5

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

Schema description coverage is 0% across four parameters, so the description must compensate. It explains app_id and activity, but leaves device and package entirely undocumented. Worse, the coexistence of app_id and package is never reconciled, leaving ambiguous which one to pass and whether one is an alias for the other.

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?

States a specific verb (start) and resource (app), and clarifies the id format as Android package / iOS bundle id. However, it does not differentiate itself from the sibling launch_app, which appears to serve a nearly identical purpose, leaving the agent unable to choose between them from the description alone.

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 on when to use start_app versus launch_app, open_and_settle, or open_deeplink. The optional activity parameter is mentioned but no condition for supplying it is given. The agent must infer usage from the name alone.

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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