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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety and reach profile is covered. The description adds that the score is "indexed 0–100" and that the breakdown is "complete available" signals, hinting that some signals may be absent — useful, but no mention of auth, rate limits, or caching. Adequate against the lower annotated bar.

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?

A single front-loaded sentence with no filler; the output shape (score plus signal breakdown) is stated immediately and nothing is repeated from the schema or annotations.

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 must convey return values, and it does name both the 0–100 score and the signal breakdown including its partial nature. It stops short of indicating breakdown structure or what an empty signalless listing returns, but this is largely complete for a read-only diagnostic 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 description coverage is 100%, with both parameters documented (retailer enum meaning, product_id format) and the enum constrained in-schema. The description only implies the two parameters jointly identify "one retailer listing", adding little beyond the schema — baseline 3.

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 ("Return") and resource ("indexed 0–100 marketplace-evidence score and complete available signal breakdown") scoped to "one retailer listing". This implicitly separates it from the store-level sibling check_store_score, though no sibling is named outright.

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 gives no when-to-use condition, no prerequisites, and does not contrast itself with check_store_score (store vs. single listing) or compare_products. An agent must infer the product-level vs. store-level distinction entirely from the tool name.

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