scan_view

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

With no annotations, the description carries the full burden. It usefully discloses a behavioral trait beyond the schema: a red pixel ruler is rendered over the output for coordinate reporting. It does not state that this is a read-only/non-mutating operation, nor what the return artifact is (image?), which matters for an agent deciding how to consume the result.

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 tight sentences with no filler; the core action is front-loaded and the region syntax follows immediately. Slightly dense, but every clause contributes.

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 annotations and no output schema, with only 1 of 5 parameters documented, so the description is the sole source of context. It covers the viewing purpose and the ruler/coordinate rationale well, but omits what max_px and grid control and what the tool returns, leaving meaningful gaps for an agent.

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. It does resolve the trickiest parameter, defining region as [x0,y0,x1,y1] and clarifying the dual pixel/fraction units. It leaves grid, page, max_px, and scan_id entirely unexplained, so four of five parameters remain undocumented.

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?

States a specific verb ('Look at') and resource (a page or zoomed region of a scan), which is clearly distinct from mutation siblings like scan_calibrate or scan_overlay. It does not explicitly name which sibling it replaces, but the purpose is unambiguous.

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?

It hints at context by saying the ruler exists 'so you can report pixel positions for scan_calibrate / placement,' which implies this is a step preceding calibration. However, it never states when to use this versus scan_overlay, scan_preview, or scan_calibrate directly, nor any preconditions (e.g., scan must be opened first).

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