capture_screen

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

No annotations are provided, so the description carries the full burden. It discloses the Screen Recording permission requirement and explains the impact of max_size on speed and tokens. However, it does not clarify if the operation is read-only or destructive (it is read-only by nature), and does not mention error scenarios or side effects.

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 and well-structured: first sentence states purpose, then parameter explanations in a clear list format, ending with return type and permission note. No wasted content.

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 tool's simplicity (2 parameters, no output schema), the description is fairly complete. It covers purpose, parameter semantics, return type, and a key requirement (permission). Minor gaps include format of the image and error handling, but these are not critical.

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 has 0% description coverage. The description adds significant meaning: explains display values (0=all, 1=main, 2=secondary) and max_size with usage advice (400 for quick, 1200 for detail). This compensates well for the missing schema descriptions.

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 captures a screenshot of the full screen or a specific display, using specific verbs and resource. However, it does not explicitly differentiate from sibling tools like capture_screen_region or capture_window_tool, though the purpose is implied by the name and context.

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 its siblings (e.g., capture_screen_region for a region, capture_window_tool for a window). The description gives advice on max_size parameter values for quick checks vs. detail, but not for tool selection.

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