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

Annotations already declare readOnly, idempotent, non-destructive, closed-world behavior. The description adds genuine value beyond that by spelling out the payload contents (bilingual definitions, pronunciation, aliases, component names per platform, prompt, Q&A, related patterns, catalog URL), which tells the agent what it will actually receive.

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-loaded with the core action, followed by a colon-list of return contents and a routing clause. Dense but every element is informative; the only minor cost is that the long field enumeration could be trimmed for a single-entry lookup.

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 the return value and does so thoroughly, while also covering the single input and the id-discovery path. Nothing an agent needs to call and interpret this tool 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% for the single id parameter, and the schema already documents both the format and the sibling that lists all ids. The description's 'Takes an id' and the 'tabbar'/'bottomsheet' examples largely restate the schema, so it stays at the baseline.

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 (Returns) and resource (the full CatchUI entry for one UI pattern), scoped to retrieval by id. The enumeration of returned fields makes it immediately distinguishable from siblings like list_ui_patterns or search_ui_patterns, which return sets rather than full entries.

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 says it takes an id and routes the agent to search_ui_patterns to find ids from descriptions, with the schema adding list_ui_patterns as the id enumerator. Clear context for use, though there is no explicit when-not condition (e.g. preferring the narrower get_implementation_prompt or get_ui_component_names siblings when only one facet is needed).

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