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 burden. It describes the tool as a comparison operation ('Compare two UI screenshots'), implying a read-only, non-destructive behavior. It does not mention side effects, but for a comparison tool this is adequate. No contradictions.

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 sentence that efficiently communicates the tool's purpose without wasted words. It is front-loaded with the action 'Compare' and specifies the exact outputs. Ideal 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?

The description explains the tool's purpose but does not describe the output format or return value. Since no output schema is provided, the description should hint at what the tool returns (e.g., a list of differences with coordinates). This omission reduces completeness.

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 100% with clear parameter descriptions. The tool description adds only context ('design vs implementation') beyond what the schema already provides. Baseline 3 is appropriate as the schema already handles parameter documentation.

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 states the tool's function: comparing two UI screenshots for visual differences, layout drift, style inconsistencies, missing elements, and typography discrepancies. It uses specific verbs and a clear resource 'UI screenshots', and distinguishes from siblings by focusing specifically on UI diffing.

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 design vs implementation screenshots, but does not explicitly state when to use this tool over siblings (e.g., 'image_analysis' for general comparison). No 'when not to use' or alternative recommendations are provided.

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