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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds substantial behavior beyond that: it renders a composite, enumerates exactly what is measured (pixel size, aspect ratio, border whiteness, product fill ~85%, edge touching), and describes the return structure. This is rich, non-redundant disclosure.

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?

Front-loaded with purpose, then behavior, then return shape, then the marketplace table. Dense and mostly earning its place, though the marketplace enumeration is lengthy and could be slightly compressed.

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?

No output schema exists, but the description explains the return fields (rule, pass, measured, required, fix) and the marketplace-specific targets, so an agent has everything needed to interpret results and act on them.

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 a marketplace enum, so baseline is 3, but the description adds real meaning: the required pixel dimensions per marketplace (amazon 2000x2000, etsy_landscape 2700x2025, etc.), which is not in the schema. The image param is not elaborated, keeping it from a 5.

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 and resource ('check whether a photo is ready to list on a marketplace') and immediately scopes it as non-mutating ('without changing it'). This clearly distinguishes it from siblings like product_shot or export_photo that act on the image.

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?

Frames the tool as a pre-listing validation step and explicitly routes to the fix path ('usually product_shot with that marketplace'). No explicit when-not or exclusion, but the usage context and alternative are clear.

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