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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=true. The description adds significant value by explaining the semantics of 'orderable: false', clarifying that it means no storefront prices and that the product cannot be bought through this API. It also warns against misrepresenting catalogue identity as availability. No contradiction with annotations.

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 sentences, each earning its place. The first sentence states the purpose and scope, the second gives usage guidance, and the third explains a critical behavioral nuance. No fluff or repetition.

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?

Given the complexity (two parameters, no output schema), the description adequately covers the return structure by mentioning 'chain-specific item code, display name, and package size' and the orderable flag. However, it does not explicitly describe the top-level product fields (e.g., id, gtin) or the overall shape of the response. Slightly incomplete for a fully self-contained description.

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 baseline is 3. The description adds 'by product_id (UUID) or GTIN barcode', but the schema already describes each parameter with similar clarity (e.g., gtin: 'GTIN/barcode, used only if product_id is omitted'). The description does not add meaningful new semantics beyond the schema.

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 clearly states 'Fetch full detail for one canonical product by product_id (UUID) or GTIN barcode, including every per-chain listing.' This is a specific verb-resource combination that distinguishes it from sibling tools like search_products.

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?

Explicit guidance: 'Use after search_products to confirm identity, or directly when the GTIN is already known.' It also provides clear instructions on interpreting orderable: false, telling the agent when not to present a chain as purchasable.

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