compare_images

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

Without annotations, the description must reveal behavioral traits. It only states the basic function and does not disclose whether the tool modifies images, requires special permissions, or what the output format is (despite having an output schema). The description lacks details about side effects, constraints, or exact analysis capabilities.

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?

The description is concise with two sentences. The first sentence delivers the core purpose, and the second lists relevant use cases. No redundant or unnecessary words, well-structured and easy to parse.

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 the existence of an output schema, the description does not need to explain return values. It adequately covers the tool's purpose and use cases. However, it could mention that the tool supports more than two images (implied by '2+' in schema) or hint at output type, but overall it provides sufficient context for a simple comparison tool.

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 the schema already documents all parameters. The description does not add additional context beyond the schema, such as clarifying the effect of 'use_grounding' or the format of 'prompt'. Baseline 3 is appropriate as the description adds no extra value over the schema.

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 purpose: 'Compare two or more images and analyze differences.' It identifies the specific action (compare) and resource (images), and lists use cases like A/B testing and design review, which distinguishes it from siblings like edit_image or detect_objects.

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 lists common use cases ('Useful for A/B testing, design review, before/after comparison, and change detection'), giving context for when to use it. However, it does not explicitly exclude alternatives or provide when-not-to-use guidance, missing an opportunity to differentiate from similar tools like analyze_image.

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