screenshot_region

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

No annotations are provided, so the description must carry the full burden of behavioral disclosure. It only states the action and input format, but does not mention that a file is saved, where it is saved, default filename behavior, or what the tool returns. This is a significant gap for a screenshot tool that likely creates image files.

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, concise sentence with no redundant information, front-loading the core purpose and input method. It is well-structured and easy to parse.

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 the absence of annotations and output schema, the description is too thin to fully understand the tool's behavior, such as file output, naming defaults, and error handling. It does not explain what happens after the screenshot is taken or how the 'active_window' option behaves across platforms.

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?

The schema already provides 100% coverage with descriptions for both 'region' and 'filename,' and the description merely restates the region format without adding new details about coordinate systems, units, or default values. The 'filename' parameter is not mentioned in the description, so no added value beyond the schema.

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 clearly states the tool takes a screenshot of a specific screen region, distinguishing it from the sibling 'screenshot' tool by emphasizing 'specific region.' It also mentions the two input modes, making the purpose unmistakable.

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 description implies usage for capturing a defined screen area but does not explicitly contrast it with the sibling 'screenshot' tool, nor does it provide when-to-use/when-not-to-use guidance or exclusions. Users must infer that full-screen captures would use 'screenshot.'

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