Screenshot

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

With no annotations, the description carries the full burden and does real work: it discloses the 800px JPEG downscale default, the native PNG override, the actionable-error failure path when the image is too large, and that mask is iOS-only. It omits operational context such as permission or device prerequisites.

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?

Two sentences, front-loaded with the core action, with the two modes laid out in a readable order. The second sentence is dense and slightly run-on, but every clause carries distinct information.

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?

No output schema and no annotations, yet the description states what is returned in both modes (inline image vs. file path) and the failure behavior, which is the key completeness requirement here. Only the undocumented `device` parameter keeps it from being fully self-sufficient.

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%, so the description must compensate, and it explains four of five parameters: output_path (save vs. inline), full_res (native PNG), format (png/jpeg), and mask (iOS-only). The `device` parameter is left entirely unexplained, which is the main remaining gap.

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?

Opens with a specific verb and resource ('Capture the current screen') and immediately splits into two well-defined modes (inline return vs. file save). It is clear what the tool does, but it never names the obvious alternatives (record_video, read_screen_text) to sharpen the boundary.

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?

Gives explicit conditions for the two main branches: 'Without output_path...' versus 'With output_path...', plus the full_res escape hatch for native resolution. It tells the agent how to choose a mode, but offers no guidance about when to reach for this tool instead of sibling capture/inspection tools.

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