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

Annotations cover the safety profile (not read-only, non-destructive, non-idempotent, closed-world), and the description adds substantive context beyond them: the GTIN check digit is validated server-side, a GTIN is unique to one product, and the call is gated to Business plans. It stops short of saying what error arises on a duplicate GTIN or license failure.

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?

Three tight sentences, front-loaded with the action and its outcome, then constraints. No filler, though the checkout/QR framing is slightly promotional relative to the operational facts.

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?

An output schema exists, so return values need no explanation, and the description covers validation, uniqueness, and plan gating for a 4-parameter mutation. Only the duplicate-GTIN failure mode is left unstated, which for a non-idempotent create is a meaningful but small gap.

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 75%, and the description adds a hard constraint the schema does not convey — the GTIN must be a genuine GS1-licensed value whose check digit is verified on submission. The brand field remains undocumented in both places, keeping this below a 5.

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 ('Create a GS1 Digital Link product from a GTIN') and explains the resulting artifact — a QR that scans at checkout and resolves to the brand's URL. This cleanly separates it from create_qr_code, which produces a code without the GS1 product record.

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?

'Business plan only' and 'One GTIN is one product' give real preconditions, and the url parameter hints at the deferred-link workflow. But there is no explicit statement of when to use this versus create_qr_code or bulk_create_qr_codes, and no guidance on what to do if the GTIN already exists.

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