Match by EAN

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

Annotations already declare read-only, open-world, idempotent, and non-destructive behavior. The description adds valuable context beyond these: the authentication requirement ('Pro API key required') and the semantics of non-current matches ('may be upcoming or historical unless current_only is true'). This clarifies default behavior without contradicting 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 three short, front-loaded sentences with no redundant wording. Each sentence adds distinct information: purpose, requirement, and behavioral nuance.

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 read-only lookup tool, the description covers purpose, a prerequisite, and a key behavioral aspect. It does not explain the 'exclude_retailer' parameter or return format, but the absence of an output schema and the presence of strong annotations reduce the need for extra detail. Overall, the essential context is provided.

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 0%, so the description must compensate. It only indirectly references 'current_only' through the clause 'unless current_only is true', but does not explain 'exclude_retailer' or its behavior. The 'ean' parameter is obvious from the name, but the lack of explicit parameter semantics for most fields leaves a notable gap.

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 uses a specific verb ('Find') and a specific resource ('products with the same EAN across retailers'), making the tool's core purpose immediately clear. It also implicitly distinguishes itself from sibling tools like 'match_product' or 'search_products_by_name' by focusing on EAN-based cross-retailer matching.

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 states a usage prerequisite ('Pro API key required') but does not explicitly compare with alternatives or state when to use this tool over siblings. The phrase 'across retailers' hints at its unique role, but there is no direct 'use this instead of X' guidance.

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