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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely new behavioral context not present in structured fields: the per-call cost (30 points) and a full enumeration of returned fields in the absence of an output schema. It does not cover failure modes for bad URLs/IDs, which keeps it from a 5.

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 field list is front-loaded and informative, but the entire description is duplicated verbatim in English and Korean, roughly doubling its length without adding information. Placement of the cost note at the end is reasonable, but the redundancy is a real efficiency cost.

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?

With no output schema, the description correctly compensates by enumerating the returned fields, and it adds cost information the annotations lack. Combined with annotations covering the read-only/open-world profile, an agent has nearly everything needed; only error behavior and invalid-input handling are 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 100%, so the schema already documents url and product_id, including the 'one of these is required' constraint in Korean. The description only restates the two input modes ('by URL or product id') without adding syntax, format, or precedence rules, so the baseline 3 applies.

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 names a specific resource (Coupang product) and enumerates the exact data returned (title, prices, discount, rating, reviews, stock, seller, options, categories, images), so the agent knows exactly what it retrieves. The vendor name implicitly separates it from amazon_product and naver_shopping_product siblings, but it never explicitly contrasts them, so it stops short of a 5.

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?

There is no statement of when to use this tool versus amazon_product or naver_shopping_product, and no prerequisites or exclusions are given. The only usage-adjacent information ('by URL or product id') is really input format, not selection guidance, so an agent must infer the Coupang-only scope from the name.

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