compare_image_with_url

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

With no annotations, the description carries the full burden. It discloses that a screenshot is taken, pixel-by-pixel comparison occurs, results include statistics and a diff image, and diff output path behavior (defaults to timestamped file). However, it does not mention network requirements, timeouts, or potential side effects like file creation on disk.

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 sentences: first defines the tool's core function, second elaborates on the process. No redundant information, and essential information is front-loaded.

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 5 parameters, no output schema, and no annotations, the description covers the main purpose and outputs but lacks details on return value format (e.g., difference statistics structure) and potential limitations (e.g., screenshot viewport size). Still largely adequate.

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%, so baseline is 3. The description adds value by explaining that the diff_output_path defaults to a timestamped file, and that includeAA controls anti-aliasing inclusion, which is not fully covered by schema descriptions. This extra context justifies a 4.

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 verb 'compare' and the unique resources: a local image file and a screenshot from a URL. It distinguishes itself from siblings compare_images and compare_urls by specifying this hybrid scenario.

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?

While the description implies the tool is best for comparing a local image with a webpage screenshot, it does not explicitly state when to use it over siblings or provide when-not/exclusion criteria.

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