Capture a screenshot of a specific application window by app name on macOS. Optionally set a custom save path for the image.
Capture a specific window by app name
| Name | Required | Description | Default |
|---|---|---|---|
| app_name | Yes | Name of the application (e.g., "Safari", "Terminal") | |
| save_path | No | Optional custom save path |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the action and target but does not describe what the capture returns or where it is saved, whether window content is included, or any permission/visibility requirements. This leaves the agent with gaps about side effects and prerequisites.
Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.
Is the description appropriately sized, front-loaded, and free of redundancy?
The description is a single front-loaded sentence containing only the essential action and selection criterion, with no filler or redundancy.
Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.
Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?
Given that no output schema or annotations exist, the definition should clarify the output behavior, such as a saved image path, and constraints like window visibility or permissions. It does not, so the definition is incomplete for a tool with no structured metadata to fill the gaps.
Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.
Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?
Schema coverage is 100%, so the schema already documents both parameters. The description's 'by app name' reflects the required app_name parameter but adds no new meaning about save_path or value formats.
Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.
Does the description clearly state what the tool does and how it differs from similar tools?
The description uses a specific verb 'Capture', identifies the resource as 'a specific window', and includes the selection criterion 'by app name'. This clearly separates it from sibling tools like capture_fullscreen and capture_region.
Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.
Does the description explain when to use this tool, when not to, or what alternatives exist?
The phrase 'by app name' implies the tool should be used when the agent needs to capture a window belonging to a known application. However, it does not explicitly mention alternatives or state when not to use this tool over capture_fullscreen or capture_region, leaving usage guidance implicit.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.