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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safe-read nature is covered. The description adds that every purchasable size with its own price and availability is returned, but since an output schema exists this is somewhat redundant and no other behavioral context (rate limits, auth, staleness) is given.

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?

Two tight sentences with zero filler; the capability is front-loaded and the prerequisite workflow follows. Every sentence earns its place.

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 tool is simple (2 required params), an output schema exists so return values need not be explained, and the description covers the key workflow prerequisite. Annotations carry the safety profile; only minor behavioral detail is absent.

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% - slug is documented as the product URL slug from a search result's id field, and gender as department (women, men, kids). The description adds no format or syntax beyond what the schema already provides, so baseline 3 applies.

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 (Fetch) and resource (full Farfetch product details) with a clear scope that includes purchasable sizes with price and availability. It distinguishes itself from farfetch_search by naming it and explaining the relationship.

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 to use farfetch_search first to obtain the listing's gender and URL slug before calling this tool. This tells the agent both when to use this tool (after discovery) and which sibling precedes it, leaving nothing to inference.

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