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

With no annotations provided, the description carries the full behavioral burden. It usefully discloses the result-count bounds (min 1, max 10) and a per-call billing cost (~0.85 avg credits), which is real value beyond the schema. But it omits auth/permission requirements, error behavior, and what the response looks like.

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?

Two dense clauses with the core action front-loaded and no filler. Every element (search keys, result range, billing) earns its place, though the semicolon-joined billing note reads slightly like metadata appended rather than integrated prose.

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?

For a tool with no output schema and no annotations, the description covers the input action and result cardinality but leaves the return shape and error/empty-result behavior unexplained. It is adequate but not complete for an agent to predict what comes back.

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 all four parameters (query, marketPrices, historyPrices, preferredMarkets) are already well documented in the schema itself, including credit costs and the dependency of historyPrices on marketPrices. The description adds no parameter-level meaning beyond that, so the baseline of 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?

States a specific verb and resource ('Searches for products by barcode or name') and quantifies the result set (1–10 products). However, it does not distinguish itself from the close sibling get_api_external_getProducts or get_api_external_product_of_market, so an agent cannot easily tell which search/list tool to pick.

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 never states when to use this tool versus the many sibling lookup tools, nor prerequisites such as whether marketPrices/historyPrices should be toggled for a given intent. Usage context is implied only by the parameter names in the schema.

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