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

Annotations cover readOnlyHint and openWorldHint, so safety is handled. The description adds substantive behavior beyond that: availability is described as 'live', reviews are conditional ('when the product has any'), and it discloses the not-found error path for unrecognized ids.

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?

Front-loads the return payload, then ID sourcing, then error behavior. Three sentences, all earning their place, though the first is densely packed and slightly long.

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 an existing output schema, the description need not explain return values, yet it still summarizes them, covers how to obtain the required ID, and documents the failure mode. Nothing needed to call the tool correctly is missing.

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 baseline is 3, but the description adds real value: it specifies the two valid sources for product_id and clarifies that the URL slug itself is not needed, reducing ambiguity about ID format.

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/resource (one product's full detail) and enumerates the payload: per-SKU color/size, price, sale status, live availability, aggregate rating, and reviews. It explicitly distinguishes itself from lululemon_category, so an agent can route without opening schemas.

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?

Names the sibling it is not (lululemon_category) and clarifies that product_id originates from a lululemon_category result's id field or a product URL's trailing segment. Clear context, though there is no explicit when-not-to-use beyond the category exclusion.

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