capture_region

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

Describes coordinate modes and return type. No annotation provided, so description carries burden. Lacks details on edge cases (e.g., out-of-bounds) or side effects, but captures the essential behavior.

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?

Well-structured with Args section. Front-loaded with purpose. Efficient but somewhat lengthy due to detailed parameter descriptions; no wasted sentences.

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 capture tool with no output schema, it explains input parameters and return type. Missing some edge cases but adequate given simplicity. No annotations to offset 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 0%, yet description fully explains all 5 parameters, including the conditional behavior of x/y with title. Adds meaning beyond schema titles.

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?

Clearly states it captures a rectangular region as PNG. Differentiates from sibling tools by explaining coordinate system, but does not explicitly name alternatives for region vs window capture.

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?

Provides guidance for when to use the title parameter (offsets from window), and references list_windows for titles. However, no explicit when-not-to-use or comparison to capture_window/capture_widget.

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