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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), so the description rightly spends its words elsewhere: viewer ordering, the meaning of `worn` (false = stood beside the player rather than worn), price units in USD cents, and the freshness caveat 'More skins are added as they're processed'. That freshness note and the field-level semantics are genuinely additive beyond the annotations.

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 purpose sentence is front-loaded and the actionable instruction sits at the end, which is a sound structure. The middle is a dense run-on enumeration of output fields that would scan better as a list, but given there is no output schema, those words carry real information rather than padding.

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 no output schema, the description steps in and documents the returned columns (shortname, name, slot, group, worn, female_model, takes_attachments, skins_in_3d, prices, viewer_url, wiki page), which is what an agent needs to plan a response. Pagination is handled by the schema's page/per_page. The only soft spot is that the shape of rows when `with_skins` > 0 is not spelled out.

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%, including the full slot and group enumerations, so the schema does the heavy lifting and a baseline 3 applies. The description adds no parameter-level detail beyond what the schema states — the `with_skins` behavior ('N most expensive 3D skins, 0 = counts only') and slot list are already in the schema. The prose instead documents return fields, which belongs to completeness rather than parameter semantics.

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 names a specific resource and scope: every item Skin Lab has a 3D model for (clothing, armour, guns, tools, deployables, building skins, vehicles), in viewer order. The Skin Lab framing implicitly separates it from the general browse_items/search_items siblings, though no sibling is named explicitly. An agent can tell this is a coverage/catalog listing for the 3D viewer, not a general item search.

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?

It gives one concrete use case — 'Use this to see which items and slots it covers; give the user the viewer_url' — which tells the agent when this tool is the right pick and what to do with the result. There is no explicit when-not guidance and no named alternative for adjacent tasks (e.g. fetching a single item's skins), so routing between siblings is left to inference.

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