compare_reference_image

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

The description explains the action of capturing and compositing, but lacks details on side effects, error behavior (e.g., missing reference), or whether it is destructive. With no annotations, more transparency would be beneficial.

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 short, front-loaded with the purpose, and lists parameters concisely. No unnecessary information.

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 does not mention the return value (e.g., composite image format) or error handling. Given no output schema, this is a significant gap. It also assumes familiarity with store_reference_image.

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?

The description adds brief context for each parameter (reference_name from store_reference_image, angle as viewport angle, max_size as tile size), which is helpful given 0% schema coverage. However, it could specify valid angle values and units for max_size.

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 it captures the viewport from a named angle and composites it with a stored reference image. This distinguishes it from similar tools like capture_viewport_angle (just capture) and diff_images (arbitrary images).

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 mentions that reference_name is from store_reference_image, implying it should be used after storing a reference. However, it does not explicitly state when not to use it or list alternatives (e.g., diff_images for arbitrary comparisons).

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