screenshot

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

With no annotations, the description carries the full behavioral burden. It discloses the output format, base resolution, and default scaling, but does not mention read-only safety, device readiness requirements, latency, or whether it has 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 a single front-loaded sentence with no unnecessary words. It efficiently conveys the core output and scaling behavior.

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 one-parameter screenshot tool with no output schema or annotations, the description covers the essential output and scaling behavior. It could be more complete by noting read-only safety or return representation, but it is largely sufficient for correct 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?

The only parameter, scale, has 0% schema description coverage, so the description must compensate. It does so by stating the default value (2) and that the screen is scaled down by this factor from 1125x2436, adding meaning beyond the schema's min/max bounds.

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 identifies the resource and output format: a PNG of the phone screen. It adds resolution and scaling details, though it does not explicitly name a capture verb or differentiate itself from siblings beyond the unique screenshot concept.

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?

There is no guidance on when to use this tool versus alternatives such as inspector_raw or other visual inspection tools. The description only states what the output is, leaving usage context implicit.

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