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

Annotations already indicate readOnly, idempotent, and non-destructive. The description adds rich behavioral detail by enumerating the full set of returned data (description, price, media, videos, size guide, per-variant stock, buy links) and noting the response includes the product image, which goes beyond what annotations state.

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 two tight paragraphs, front-loaded with the core purpose and followed by usage guidance and output specifics. Every sentence provides value without redundancy or filler.

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's simplicity (one parameter, no output schema), the description is fully complete. It covers what the tool returns, how to use it, where the parameter comes from, and the downstream action (build_cart). Annotations cover safety, leaving no gaps.

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?

The schema covers productRef with a basic description, but the tool description enhances it by explaining that productRef comes from search_products or browse_products and is used to identify the product. This adds meaningful context beyond the schema's one-line definition.

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 opens with 'Load full details for one product by its productRef', using a specific verb and resource. It clearly distinguishes this tool from siblings search_products and try_on by focusing on retrieving detailed product information for a single item.

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?

Explicitly instructs when to use: 'Use it to resolve the exact variantId the shopper wants before calling build_cart, and to answer fit/sizing questions from the size guide.' It also indicates the productRef comes from search_products or browse_products, providing clear context and sequencing.

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