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

readOnlyHint=true and openWorldHint=true already cover the safety/scope profile, so the description's added value is the enumeration of returned fields and the cross-tool usage note. It doesn't discuss pagination, completeness guarantees, or whether the directory is exhaustive, so a mid score is right.

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?

A single sentence that front-loads the resource, then the return fields, then the actionable integration tip — no 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?

With an output schema present, return values need not be explained, and the description covers purpose, scope (per department), and downstream use. Nothing critical is missing, though it could note directory ordering or completeness.

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?

Only one parameter (gender) at 100% schema coverage, where the schema already documents 'Department: women, men, kids'. The description references a department but adds no format or constraint detail beyond the schema, 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/resource pair ('department's full designer directory') and enumerates the returned fields (name, slug, URL), which lets an agent distinguish it from farfetch_categories and farfetch_product 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?

Explicitly routes the agent: each slug is usable directly with farfetch_search's designer filter, making the downstream handoff clear. It doesn't state when to prefer this over sibling listing tools like farfetch_categories, so it stops short of a 5.

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