lookupBarcode

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

Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds valuable behavioral context by stating that data is community-contributed and confidence is medium, which helps the agent calibrate trust in the result. 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?

Two sentences, front-loaded with the main purpose and source, followed by a meaningful data-quality caveat. There is no filler or repetition of schema details.

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 simple one-parameter lookup with an output schema and strong annotations, the description covers the input context, return granularity, and trustworthiness. The main missing piece is explicit guidance on how this tool relates to sibling lookup tools, but the rest of the context is adequately supplied.

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 0%, so the description carries some burden for explaining the parameter. It adds context by linking the barcode to packaged products and Open Food Facts, but it does not elaborate on barcode format or example values. The schema's pattern and property name already provide the basic validation 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 what the tool returns — per-100g macros for a packaged product from Open Food Facts — and the name plus barcode schema identify the lookup mechanism. It does not explicitly distinguish this from the sibling getFoodMacros, so it misses some sibling differentiation, but the core purpose is unambiguous.

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 when to use it: when you need per-100g macros for a packaged product identified by barcode. It also alerts the agent to data-quality limitations. However, it gives no explicit guidance about when not to use it or how it compares to alternatives like getFoodMacros or searchFood.

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