List built-in style snippets

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

Annotations already declare readOnly/idempotent/non-destructive/openWorld=false, so the safety profile is covered. The description adds genuinely new context: it reads the module-level `STYLE_SNIPPETS` constant and makes no Home Assistant call, which tells the agent this is an instant, offline lookup. It stops short of richer traits (cost, ordering guarantees) but goes beyond what structured fields provide.

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-loads the purpose then a short behavioral note and clearly labeled Use/Not-for/Returns sections. Every line is load-bearing, though the 'Returns:' line slightly duplicates the existing output schema and is marginally redundant.

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 a 0-parameter schema, full annotation coverage, and an output schema present, the description supplies exactly the missing routing and no-I/O context. Nothing an agent needs to call this correctly 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?

The tool takes zero parameters, so the baseline is 4 with no compensating explanation required. The description correctly adds no invented 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?

States a specific verb+resource ('List built-in Card Builder style snippets') plus the shape of the returned data (name and style category). It explicitly distinguishes itself from `card_builder_list_style_categories` and `card_builder_get_style_snippet`, so an agent can route correctly without opening any schema.

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?

Uses explicit 'Use when:' and 'Not for:' blocks, naming the alternative tools for each excluded case and the downstream tool (`card_builder_build_styles`) it composes with. Nothing about selection 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.