Compare Images

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

No annotations are provided, so the description carries the full behavioral burden. It discloses one useful prerequisite (a configured VLM provider), but says nothing about failure behavior when no provider is set, whether image data leaves the machine, rate/cost implications, or whether the two paths must share format or dimensions.

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 short sentences, front-loaded with the action and followed by the prerequisite. Nothing is padded, though brevity here shades into under-specification rather than efficiency.

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?

An output schema exists, so return values need not be explained. For a two-parameter tool this is borderline adequate, but the type of comparison (semantic diff, similarity score, description comparison) and the input path semantics remain unaddressed.

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 description coverage is 0% for both parameters, so the description must compensate and does not. It never mentions img1_path or img2_path, their expected format, whether they are local paths or URLs, or ordering semantics (does img1 vs img2 matter for the comparison?).

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?

States a specific verb (Compare) and resource (two images) plus the mechanism (VLM), which is enough to distinguish it from the mouse-control siblings. It does not, however, differentiate itself from analysis-oriented siblings like analyze_screenshot or describe_environment, which plausibly also use a VLM.

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 only guidance is a prerequisite ('Requires a configured VLM provider'). There is no statement of when to choose this over analyze_screenshot, capture_and_analyze, or describe_environment, nor any exclusions or preconditions on the images themselves.

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