product_lookup

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

With no annotations present the description carries the full burden, and it does disclose two high-value operational traits: a per-call cost of $0.005 USDC and a p99 latency of 2500ms. It stops short of describing failure/not-found behavior or coverage limits across the three databases, which a lookup tool with no annotations should ideally state.

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?

One front-loaded sentence opens with the tool's identity and purpose, then enumerates sources, outputs, the parameter constraint, and cost/latency. The em-dash chain is dense but every clause carries information; nothing is padded.

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?

There is no output schema, so the inline enumeration of returned fields (name, brand, quantity, categories, ingredients, allergens, labels, nutrition, Nutri-Score, NOVA, image URL) usefully compensates. Cost and latency are also covered. Only the not-found/no-data path is left unaddressed.

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%, so baseline is 3, but the description adds the explicit 8-to-14-digit constraint and marks the parameter required, which the schema only implies via 'EAN-13, EAN-8 or UPC'. That is a genuine, if modest, semantic addition over the structured field.

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?

States a specific verb and resource ('Look up a product by EAN/UPC barcode') and names the three concrete data sources plus the exact fields returned, so the agent knows precisely what it gets back. It does not explicitly differentiate itself from the sibling 'barcode' tool, so it falls short of a 5.

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?

Usage is implied by the framing (you have a barcode and want product data), but there is no explicit when-to-use/when-not guidance, no mention of what happens when a barcode is not found in any of the three databases, and no routing away from the sibling 'barcode' tool.

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