lookup_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. However, it only mentions the source and free nature, failing to disclose behavioral traits like rate limits, data freshness, authentication requirements, or whether the operation is read-only. The description is insufficient for full transparency.

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 sentence, which is concise and front-loaded with the purpose. However, it is very brief and could benefit from slight expansion for clarity, but it earns its place without waste.

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 tool has one parameter and an output schema, the description is minimally sufficient for a straightforward lookup. However, it lacks usage guidelines and behavioral transparency, making it less complete for agents that need to decide when to invoke it. The presence of an output schema reduces the need to describe return values.

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 coverage is 100% with the single parameter described. The description adds an example barcode ('4006381333931' for Nivea cream), which provides concrete formatting expectations and context beyond the schema. This enhances parameter semantics.

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 tool looks up a product by UPC/EAN barcode, specifying the source (UPCitemdb) and that it's free. This is a specific verb-resource combination, and it distinguishes itself from siblings like get_product_details or search_products, which likely use different identifiers or query methods.

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 does not provide any guidance on when to use this tool versus alternatives. It only states what it does, leaving agents to infer usage context. No exclusions or sibling tool references are given.

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