Capture any screen region by specifying coordinates, width, and height. Save the image to a file path for later use.
Capture a specific region of the screen
| Name | Required | Description | Default |
|---|---|---|---|
| x | Yes | X coordinate | |
| y | Yes | Y coordinate | |
| width | Yes | Width of region | |
| height | Yes | Height of region | |
| save_path | No | Optional save path |
Changes observed during successful MCP inspections.
v1.0.0Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations present, the description carries the full burden of behavioral disclosure, but it only restates the tool's name. It does not explain what happens to the captured image (returned vs. saved to disk), how the optional save_path interacts with behavior, which coordinate system is used, or how out-of-bounds coordinates are handled.
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 one short, front-loaded sentence with no wasted words, which is structurally clean. However, it is under-specified rather than genuinely concise: a tool with five parameters, no annotations, and no output schema needs more substance to earn its place.
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?
For a tool with 5 parameters, no annotations, and no output schema, a single clause is insufficient. Critical context is missing: return-value behavior, save_path behavior, coordinate system, and which sibling tools this replaces. An agent cannot fully determine how to invoke this tool correctly or interpret its result.
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 description coverage is 100%, so the schema already documents all five parameters. The description adds marginal meaning by referring to a 'specific region,' which maps to the x/y/width/height parameters, but it does not clarify save_path semantics or whether capture returns image data when save_path is omitted.
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') with a clear resource ('a specific region of the screen'), and the qualifier 'specific region' implicitly differentiates it from siblings like capture_fullscreen and capture_window. However, it does not explicitly name these alternatives, so an agent must infer the distinction.
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?
No guidance is provided on when to use this tool versus capture_fullscreen, capture_window, or monitor_screen_region. The description offers no context, prerequisites, or exclusions, leaving the agent to guess which capture tool fits the task.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.