UI Diff Check

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

No annotations are provided, so the description carries the transparency burden. It does disclose the scope of analysis (layout, typography, color, spacing) but stops short of describing output format, return structure, or limitations about how the comparison is performed.

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?

Single sentence, front-loaded with the verb and resource, and every clause adds meaningful detail. There is no filler or duplication of schema 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?

The description covers the core purpose but lacks any information about the return value or output structure, which is especially relevant since no output schema is provided. Combined with the absence of annotations, an agent must infer what the tool will produce. Still, the purpose and parameter contract are clear enough for minimum viable use.

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?

All six parameters have schema descriptions covering 100% of parameters, including accepted image source formats and optional model/detail/question/token settings. The tool description adds no parameter-specific detail, but the schema already provides thorough semantics, so baseline 3 is appropriate.

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 uses a specific verb ('Compare') with a clear resource ('expected and actual UI screenshots') and enumerates concrete check dimensions: visual regression, missing elements, layout differences, typography, color, spacing, and priority. This clearly distinguishes it from generic siblings like analyze_image.

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 clearly sets the context: use this tool when comparing expected vs actual UI screenshots for visual regression. It does not explicitly name alternatives or exclusion criteria, but the intended use case is unambiguous from the phrasing.

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