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

Even with readOnlyHint=true, idempotentHint=true, and destructiveHint=false, the description adds critical context: 'Does not create a cart, order, or payment' and 'Its result already renders...' It also discloses the prerequisite of reading the category catalog and the exact-once invocation requirement, which are not derivable from annotations alone.

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 fairly long but information-dense; each sentence contributes to usage or behavioral guidance. It front-loads the primary purpose and follows with key constraints. No filler is present, though it could be slightly tightened by moving the media/exclusion notes into a separate section.

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?

Given the tool has an output schema (not shown) and rich annotations, the description is mostly complete: it explains the rendered output, the cart link, and side effects. The only minor gap is the lack of explicit explanation for the 'category' parameter, which is a required input and would benefit from a note that it must match the category from the catalog read beforehand.

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 explains productHandle and selectedOptions via 'Supply the product handle and every buyer-confirmed option name/value exactly as returned by Shopify.' However, it does not explicitly mention the 'category' parameter (implied by 'major-category' but never stated) or 'referralSource' (which has a default). Thus, it only partially covers the parameter set.

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 clearly states the specific action: 'Resolve one exact live Shopify variant after reading its category catalog.' It identifies the resource (variant) and the outcome (renders product card, variant image, add-to-cart action). It also implicitly distinguishes from siblings like display_homebridge_product_media by saying 'do not follow it with...', making the tool's unique role clear.

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?

Explicit guidance is given: 'Call this tool exactly once after the buyer completes a directly purchasable configuration.' It specifies when not to use it ('do not follow it with get_homebridge_product_media or display_homebridge_product_media unless...') and provides an alternative for checkout ('use the returned attributedCartPermalink'). This fully covers when/how to use the tool versus alternatives.

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