Browse a category or brand

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

Annotations already declare readOnly=true, idempotent=true, destructive=false and openWorld=true, so the safety profile is covered. The description adds non-obvious behavioral facts: the exactly-one-of selector constraint and the quirk that the site ignores sorting on keyword listings. It stops short of discussing pagination limits or result-count behavior, so it is strong rather than exhaustive.

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 core capability and the selector constraint are front-loaded in the first two sentences, and the remaining routing guidance is dense but each clause carries actionable information. It is slightly run-on across the routing sentences, which keeps it from a 5.

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?

An output schema exists, so return-value documentation is unnecessary; the description instead covers everything needed to call the tool correctly: the selector rule, id provenance for all three selector types, price/filter sourcing, and fallbacks for keyword and rating needs. Nothing material is missing for a read-only browsing tool.

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%, so the baseline is 3. The description goes beyond the per-field descriptions by establishing the cross-parameter invariant (exactly one of category_id/brand/tag_id) and by telling the agent where each id family is sourced (mk_categories, mk_brands, mk_filters), which is not derivable from the schema alone.

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 first sentence names a specific verb (List) and resource (products of a category, brand or tag) plus the supported refinement dimensions (sorting, price range, filters). It is immediately distinguishable from mk_search (keyword) and mk_product (details) without opening either 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?

It gives concrete use cases ("cheapest Bluetooth earbuds", price-bounded power banks), states the exclusivity rule (pass exactly one of category_id/brand/tag_id), routes keyword queries to mk_search/mk_find_cheapest, and notes that rating sort is unavailable so mk_reviews should be consulted instead. Alternatives are named with the condition that selects them.

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