Brand and spec filters of a category

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

Annotations already cover safety (readOnly, idempotent, non-destructive, open-world), and the description earns credit by disclosing result-shape caveats: brands are only the category's top brands, spec groups vary by category and may be absent, and option ids are unique per option with at most one pick per group. It stops short of describing output structure in detail, but no output schema exists to rely on.

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 purpose sentence followed by a workflow plus constraint sentences; no filler. The second paragraph is denser and mixes guidance for a different tool's parameters, which slightly blurs the structure.

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?

For a single-parameter lookup with rich annotations and no output schema, the description supplies what an agent needs: what is returned, the top-brands limitation, the possibility of no spec groups, and the selection rule. Only minor gaps remain, such as the exact response shape or empty-category behavior.

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% and the single category_id parameter is fully described in-schema (including an example), so the description does not need to re-document it. It adds only indirect meaning by explaining how the returned ids feed into em_search, which is useful but not parameter-level detail.

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 and resource — lists brands and spec filters for one category, with ids — which is clearly distinct from em_search (product search), em_categories (category list) and the other siblings. An agent can tell immediately what this returns.

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 to call it before em_search when the user wants a brand or spec, and gives a concrete example ('8GB RAM Samsung phones'), which is strong routing guidance. It loses a point because 'pass the brand id as brand_id and the option ids as attributes' is ambiguous about which tool those parameters belong to (they are em_search's, not em_filters'), which could briefly mislead an agent reading only this definition.

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