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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so safety is covered. The description adds genuinely useful context beyond that: the exact catalog size (61), the grouping by family, and the shape of each returned entry — meaningful for a tool with no output schema.

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 front-loaded sentence that leads with the action and scope, then packs the return fields, grouping, and filter into one clause. No filler or repetition despite the density.

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 carries the burden of describing returns and does so well (ids, names, definitions, grouping). Minor omissions remain — ordering within a family and whether results are paginated or stable across calls — but these are low-impact for a 61-item static catalog.

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% and the single parameter is fully documented with an enum in the schema itself. The description restates the enum values and the optionality ('optionally filtered to one family') but adds no format or edge-case semantics beyond what the schema already provides, so the baseline of 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 precise verb and resource ('Lists the 61 UI patterns in CatchUI's curated catalog') and pins the scope as the full catalog rather than a query, which is what separates it from search_ui_patterns and get_ui_pattern. It also enumerates the returned fields (ids, English/Chinese names, one-line definitions), so an agent knows exactly what this call yields.

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?

The description explains that the family filter is optional and enumerates the valid families, implying the usage pattern (call with no argument for the full catalog, with a family to narrow it). However, it never names an alternative or states when to prefer search_ui_patterns or get_ui_pattern over this, so the routing guidance is inferred rather than explicit.

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