capture_screen_region

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

No annotations exist, so description carries full burden. It mentions returning an Image and explains parameters, but lacks details like coordinate system scope (primary display only?) or permission requirements. Adequate but not thorough.

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 concise, front-loads the purpose, lists parameters clearly, and includes a usage tip. Every sentence is useful, no fluff.

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 no output schema, description states return type (Image) adequately. Covers parameters and usage hint. Could mention if coordinates are screen-relative, but it's implied by '0 = left/top edge of screen'. Nearly complete.

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 0%, but description provides clear explanations for all 5 parameters including default for max_size. This adds significant value beyond the schema's just names and types.

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 'Capture a specific rectangular region of the screen', which is a specific verb+resource. It distinguishes from siblings like capture_screen (full screen) and capture_window (window).

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?

Explicitly advises to use capture_screen first to see the full screen and identify coordinates, providing clear context for when to use this tool. No exclusion statements, but the guidance is helpful.

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