compare_ui_screenshots

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

No annotations are present, so the description must fully disclose behavior; however, it only states that visual differences are returned without addressing side effects, limitations, output structure, or error conditions, leaving significant behavioral ambiguity.

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?

A single 11-word sentence with no filler. It is front-loaded and every word adds meaning, though it could be more explanatory without violating conciseness.

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?

Given 4 parameters, no output schema, and no annotations, the description is too sparse. It does not explain the return structure, expected input formats (beyond schema), or use cases, making it under-specified for an agent to use reliably.

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 only 25% with task, page_hint, and framework_hint undescribed. The description itself adds no parameter semantics, and while the images property has a schema description, the tool description fails to explain the other three parameters.

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 the specific verb 'Compare' with the resource 'two UI screenshots' and specifies the output as 'implementation-useful visual differences,' clearly distinguishing it from sibling single-image analysis tools like analyze_ui_screenshot.

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 usage when comparing two screenshots but provides no explicit guidance on when to prefer this over analyze_ui_screenshot or diagnose_error_screenshot, and no exclusions or prerequisites are mentioned.

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