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

Annotations already cover the safety profile (read-only, idempotent, non-destructive), and the description adds real value: per-item status and pagination means partial failures are possible, and the 1–25 cap bounds the request. It does not disclose return format or error-handling details, but with a rich annotation set and an output schema, this is solid.

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?

Three tight sentences, front-loaded with the core capability, then behavior, then exclusions. Every sentence carries information and nothing is redundant.

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 output schema handles return values and annotations cover safety, so the description needn't explain results. However, for an 8-parameter tool with very low schema coverage, it omits too much parameter and request-shape context to be fully complete.

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 only 13%, so the description must carry parameter meaning, yet it only clarifies 'exact variants' (items) and 'one market' (market_id). Six parameters including sort, audience, page_size, currency, and destination_country go unaddressed, leaving significant compensation gaps.

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 verb ('Compare'), resource ('supplied exact variants'), cardinality limit (1–25), and scope ('one market'). It's clearly a comparison tool distinct from the lookup-oriented siblings, though it never names those siblings to contrast against.

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?

It provides useful exclusions ('Does not select sellers, total a basket, or purchase') that imply when the tool is inappropriate, but never states when to use it over get_product/list_offers/search_products. Guidance is implied rather than explicit.

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