android-mcp

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start_emulator

Starts an Android emulator (AVD) and waits for boot completion, returning immediately if it is already running. Prepares a local emulator for app testing by AI agents.

Instructions

Start an Android emulator (AVD) and wait until it has booted. Returns immediately if it is already running.

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": {
      "avd": "<avd>"
    },
    "name": "start_emulator"
  }
}

Input Schema

Name	Required	Description
`avd`	Yes	AVD name from list_devices
`headless`	No	Run without a window
`cold_boot`	No	Ignore the quick-boot snapshot

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Oct 23, 2026

TDQS

A3.7/5.0

Behavior3/5

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

With no annotations, the description does disclose the two most important traits: it blocks until boot completes and it is idempotent. It omits failure behavior (nonexistent AVD, boot timeout), approximate duration, and whether the emulator persists after the call returns — gaps that matter for an unattended mutation with zero annotation coverage.

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, no filler, with the blocking/idempotency behavior front-loaded immediately after the purpose statement. Nothing to trim.

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?

No output schema and no annotations, so the description must carry the whole load. It covers the happy path and idempotency but leaves out the return value (if any), error/timeout conditions, and side effects such as a lingering emulator process — meaningful omissions for a long-running start operation.

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 coverage is 100% and each of the three parameters carries its own description, including the cross-reference to list_devices for the AVD name. The description adds nothing beyond the schema, so the baseline of 3 applies.

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?

States a specific verb (start) and resource (Android emulator / AVD) plus the post-condition ('wait until it has booted'), which makes it trivially distinguishable from siblings like launch_app (app) or list_devices (enumeration). The idempotency clause further pins down the semantics.

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 'returns immediately if it is already running' line implies it is safe to call unconditionally, but there is no explicit guidance on when to prefer it over alternatives, no stated prerequisites (AVD must already exist — only implied via the schema's 'from list_devices'), and no note on whether it must precede screenshot/tap calls.

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