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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, and the description's 'Check whether' wording is consistent with them. The description adds no additional behavioral context beyond the check semantics, but with annotations covering the safety profile, the safety burden is already covered.

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 a single, front-loaded sentence with no filler or redundant restatement of the title. Every word contributes to understanding the tool's purpose.

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?

The operation is simple, all required parameters are documented, an output schema exists, and annotations cover safety and idempotence. The description is sufficient for an agent to invoke the tool correctly; the main gap is the lack of explicit guidance about when to prefer sibling tools, though that is partly penalized in the usage dimension.

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 each parameter already has detailed documentation including GTIN normalization rules, exact banner naming, and country format. The description itself adds no additional parameter detail beyond what the schema already 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 uses a specific verb with a clear resource: 'Check whether a GTIN can ship to a specific retailer banner in a country.' This clearly separates it from sibling tools like resolve_gtin, find_retailers, or count_gtin_coverage, and the title reinforces the intent without ambiguity.

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 provides a clear use context: use this when you need to determine eligibility for a GTIN against a specific banner in a country. It doesn't explicitly name alternatives or exclusions, but the intended scenario is immediately apparent from the sentence.

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