get_product_by_barcode

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

No annotations are provided, so the description carries full burden. It only states the purpose and does not disclose behavioral traits such as read-only nature, error handling (e.g., missing barcode), or rate limits. This is insufficient for a tool with no 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?

The description is a single, straightforward sentence of 13 words. It front-loads the purpose and includes no extraneous information. Every word earns its place.

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 presence of an output schema (so return values need not be described) and a single parameter with full schema coverage, the description is adequate but not complete. It lacks information about error cases (e.g., barcode not found) or any behavioral context. For a simple lookup, it is minimally sufficient.

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%—the parameter 'barcode' already has a clear description with format and example. The tool description adds 'full nutrition facts' but that relates to the overall output, not the parameter semantics. Therefore, it adds no additional meaning beyond the schema, meeting the baseline.

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 the verb 'Get' and the resource 'full nutrition facts for a food product', and specifies the method 'by its barcode (EAN/UPC)'. This distinguishes it from sibling tools like search_products (search by text) or compare_products (comparison).

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 implies usage when you have a barcode and want nutrition facts, but it does not provide explicit guidance on when to use this tool versus alternatives (e.g., search_products for name-based lookup). No when-not or exclusion criteria are mentioned.

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