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

With no annotations provided, the description carries the burden of behavioral disclosure. It clearly signals a read operation via 'Fetch' and adds useful behavior: the result includes all retailer offers and exactly one identifier must be supplied. It does not address error cases or response format, but this is a simple read tool.

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 compact sentences with no filler. The primary behavior and key constraint are front-loaded, and every clause earns its place.

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 two-parameter read tool with no output schema, the description is mostly complete: it states what is returned and how to identify the product. It could be slightly stronger by noting what happens when no match is found or when both identifiers are provided, but it gives enough for correct invocation.

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 the schema already documents both parameters. The description adds meaning beyond the schema by explaining the priority ('slug preferred'), the fallback case ('GTIN used when slug is unknown'), and the exclusivity constraint ('Provide exactly one').

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 ('Fetch'), a clear resource ('a single full product'), and gives the lookup keys. It distinguishes itself from get_offers by explicitly including all retailer offers, so the agent can tell it apart from siblings.

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 gives clear context for when to call the tool: to fetch a single full product by slug or GTIN. It also gives selection guidance between the two parameters ('slug preferred', 'Provide exactly one'), though it does not explicitly mention alternatives or when not to use this tool.

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