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@mgcrea/mcp-ios-simulator

by mgcrea

iOS Simulator: Press Button

ios_simulator_press_button

Press the home button on an iOS Simulator to background the app under test without terminating it. Optionally wait for animations and capture a screenshot to verify the result.

Instructions

Press a hardware button. home is the way back to the home screen and the reliable way to background the app under test without terminating it.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameYesWhich button. `home` works on Face ID devices too — it is the gesture, not the physical button.
deviceNoWhich simulator: its UDID or its name as shown by ios_simulator_list. Omit it when exactly one is booted — that is the normal case, and IOS_SIMULATOR_ID pins it when it is not. Unlike simctl's own `booted`, this never picks arbitrarily between two.
settle_msNoMilliseconds to wait before the follow-up screenshot, so an animation finishes first. Raise it for a screen that loads data; a capture taken mid-transition shows neither state. This is a pause for an animation, not a wait for work to finish — which is why it stops at ten seconds. For anything longer, use ios_simulator_wait_for_element.
screenshotNoReturn a screenshot of the resulting screen. On by default, and worth leaving on: it is how you find out that the action landed where you meant it to. Turn it off only for a sequence whose intermediate states you do not need to see.

Schema Changelog

Changes observed during successful MCP inspections. Dates show when Glama detected each change.

  1. First observedv0.2.0

TDQS

A4.5/5.0
Behavior4/5

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

Annotations only supply readOnly/idempotent/destructive hints; the description adds the key behavioral consequence that home backgrounds the app without terminating it, and the schema notes that home is a gesture on Face ID devices. It does not contradict the annotations and gives useful behavioral context beyond the structured hints.

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 two short sentences with the verb and resource front-loaded and the most useful guidance in the second sentence. There is no filler or repetition of what the schema already states.

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

Completeness5/5

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

Given the rich per-parameter descriptions, the annotations, and the simplicity of the action, an agent has enough to select and invoke the tool correctly. The lack of an output schema is mitigated by the screenshot parameter explicitly describing the returned screenshot behavior.

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 baseline is 3; the tool description adds value by explaining what the `home` parameter accomplishes (returning home/backgrounding without termination). The remaining parameters are already richly described in the schema, including device-selection behavior and settle_ms semantics, so the overall parameter guidance is strong.

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 concrete action ('Press a hardware button') and immediately explains the purpose of the only supported button: returning to the home screen and backgrounding the app without terminating it. This clearly differentiates it from terminate, launch, screenshot, and other simulator actions.

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

Usage Guidelines4/5

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

It gives clear when-to-use context: use home to go back to the home screen or to background the app safely without terminating it. The settle_ms parameter description further routes longer waits to ios_simulator_wait_for_element, but the prose does not enumerate exclusions for every sibling, so it stops short of a 5.

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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