da_screenshot

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

No annotations are provided, so the description carries full burden. It transparently discloses the display range (0..32767), the special null/undefined behavior for primary display, and the PNG output format. This is a read-only capture operation, which is reasonably transparent despite not detailing file size or resolution implications.

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 efficient sentence that covers the key behavior distinctions (primary vs specific display) without extraneous detail. It's appropriately concise, though it could be marginally more structured.

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 simple 1-parameter screenshot tool, the description covers the essential behavior: what it captures, output format (PNG), and the displayId semantics. No output schema exists, but for a screenshot tool the return type is obvious. The null-handling clarification adds meaningful value for correct agent invocation.

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%, so the description must compensate. It does explain the displayId parameter semantics (null = primary display, 0..32767 = specific display). However, the range is already specified in the schema's minimum/maximum constraints, so the description largely restates schema info rather than adding substantial new meaning.

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 states a specific verb+resource ('Capture a PNG screenshot') and clarifies the behavior for both null/undefined and specific displayId values. It's clear about what the tool does, though it doesn't explicitly distinguish from siblings like da_list_displays or da_ocr.

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 when to use it (capture a screenshot) but doesn't provide exclusion guidance. It doesn't mention when one might prefer da_ocr for text extraction or how this relates to da_list_displays for finding valid display IDs. Usage context is implied rather than explicitly stated.

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