lookup_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 does disclose a meaningful behavioral trait: 'Tries Open Food Facts first, then UPC ItemDB as fallback,' which signals external data sources and ordering. However, it does not mention that this is a read-only network call, what happens when a barcode is not found, or any latency/error behavior that an agent might need to handle.

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 two short sentences with no wasted words. It front-loads the core action and followes with the fallback behavior. Every sentence adds value.

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's simplicity (one param, no output schema, no annotations), the description is mostly adequate but misses key operational details. It does not explain what the returned product data looks like, what happens if neither source returns a result, or whether the tool has side effects. An agent would benefit from one more sentence about the return or failure behavior.

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%, and the parameter is already described as 'Product barcode (EAN/UPC, 8-14 digits).' The tool description does not add any extra meaning about the barcode parameter beyond what the schema provides, so the baseline of 3 is appropriate.

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 states a specific verb and resource: 'Look up a product by barcode.' The fallback sources add clear scope and distinguish it from the many CRUD siblings, none of which do external barcode lookup. An agent can immediately identify what this tool does.

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 through the verb 'look up' and mentions the fallback order, but it does not explicitly state when to use this tool vs alternatives. There are no when-to-use or when-not-to-use conditions, and the closest sibling tools like search_foods are not referenced. The usage context is embedded but not spelled out.

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