xcode-mcp-server (drewster99)

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take_app_screenshot

Read-onlyIdempotent

Take screenshots of up to 5 windows for any app found by case-insensitive name match. Returns file paths for each captured window.

Instructions

Take screenshots of all windows for an app (case-insensitive substring match). If the app has more than one window, screenshots will be taken for up to 5 of them.

Note: Only apps with at least one on-screen window can be found by this tool.

Args: app_name: Full or partial app name to match.

Returns: Path(s) to saved screenshot file(s), one per line (max 5 windows). If multiple apps match, returns an error with the full window list.

Raises: XCodeMCPError: If no matching app found, multiple apps match, or screenshot fails.

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": {
      "app_name": "<app_name>"
    },
    "name": "take_app_screenshot"
  }
}

Input Schema

Name	Required	Description	Default
`app_name`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

First observedv0.1.0Jun 24, 2026

TDQS

A4.7/5.0

Behavior5/5

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

Annotations indicate read-only, idempotent operation. Description adds valuable context: case-insensitive matching, 5-window limit, requirement for on-screen windows, and error conditions. No contradiction with annotations.

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?

Concise and well-structured: first sentence states core purpose, followed by limitations and note, then structured Args/Returns/Raises. No extraneous content.

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?

For a simple tool with one parameter and no enums, the description covers purpose, limitations, return format, and common errors. The existence of an output schema is noted; the description sufficiently explains output.

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?

The only parameter, app_name, is described as 'Full or partial app name to match' with case-insensitive behavior. This adds meaning beyond the schema's type string, but could be more explicit about whether it's a substring or fuzzy match.

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?

Clearly states the tool takes screenshots of all windows for an app using a case-insensitive substring match. Distinguishes from sibling tools like take_window_screenshot and take_simulator_screenshot by specifying scope (app vs window vs simulator).

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?

Provides context on when the tool works (only apps with on-screen windows) and behavior (up to 5 windows, multiple apps error). Does not explicitly compare to alternative screenshot tools, but the mention of 'case-insensitive substring match' and limitation of 5 windows offers sufficient guidance.

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