KH Merch Graph

Look up one item

explain_product

Read-onlyIdempotent

Get the full record for one catalog item (Kingdom Hearts, Demon Slayer and One Piece). Pass a sku_id from discover/resolve_listing (e.g. {sku_id: "ichiban-kuji-kh-2018-a"}), or a free-text query such as {query: "Sora Bring Arts Halloween Town"} to get the best match. Returns names (en/ja), product line (maker, line type, release date), characters, original price (msrp_jpy, price_local, currency, price_basis), acquisition_type (retail, kuji, prize, …), availability (hint + confidence), typical_channels, shipping (whether it is only sold at shops that ship within Japan, so a shipping-forwarding service is needed from abroad; costs are not calculated; for Mercari/Suruga-ya items a note that Mercari's global app may allow direct purchase in some countries), size/weight, re-release dates, official (licensed or fan-made), verified (checked against the source), source_url (primary source) and page_url (the item's page on merchgraph.app; cite both).

Tool call template

This tool declares no required parameters. Add optional parameters from the input schema as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {},
    "name": "explain_product"
  }
}

Input Schema

Name	Required	Description	Default
`query`	No	Free-text product name in English or Japanese when you have no sku_id, e.g. "一番くじキングダムハーツ A賞".
`sku_id`	No	Catalog SKU ID, e.g. "ichiban-kuji-kh-2018-a". Either sku_id or query is required.

Schema Changelog

Changes observed during successful MCP inspections.

Changed2 schema fields changedOct 28, 2026

changedInput schema / properties / query / description

Previous value: -"自然文クエリ（sku_id が無い場合に使用）"New value: +"Free-text product name in English or Japanese when you have no sku_id, e.g. \"一番くじ キングダムハーツ A賞\"."

changedInput schema / properties / sku_id / description

Previous value: -"正規SKU_ID（sku_id か query のどちらか必須）"New value: +"Catalog SKU ID, e.g. \"ichiban-kuji-kh-2018-a\". Either sku_id or query is required."

First observedOct 23, 2026

TDQS

A4.4/5.0

Behavior4/5

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

Annotations already cover safety (readOnly, idempotent, non-destructive, closed-world), so added context is what counts: the description discloses the shipping-forwarding caveat, the Mercari global-app note, that costs are not computed, and that source_url plus page_url should both be cited. Those are genuinely useful behavioral facts beyond the structured fields; a 4 rather than 5 because it never mentions matching ambiguity or failure behavior for the free-text query when no match is found.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loaded with purpose and input sourcing, then the long parenthetical enumerating return fields. It is dense with no filler sentences, and the field enumeration is justified because no output schema exists, though the single sprawling paragraph could have been broken into a return-fields sentence for readability.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness5/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema and only two parameters, the description carries the return-value burden and does so thoroughly: identity, product line, characters, pricing across currencies, acquisition type, availability with confidence, shipping caveats, size/weight, licensing and verification flags, and both URLs. An agent can form a complete expectation of the response without any other source.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema coverage is 100%, so the baseline is 3; the description goes beyond by clarifying that query is a fallback used 'when you have no sku_id' and that it returns 'the best match' (i.e. fuzzy resolution rather than exact lookup), which the schema does not say. The example values largely duplicate the schema's own examples, so it earns a modest bump rather than a full 5.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose5/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Get the full record for one catalog item') plus the domain scope (Kingdom Hearts, Demon Slayer, One Piece), and explicitly distinguishes itself from discover/resolve_listing by naming them as the source of sku_id values. The name-only sibling set is disambiguated 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.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Clear routing guidance: use a sku_id obtained from discover/resolve_listing, or fall back to a free-text query for a best match. It also sets the boundary against estimate_landed_cost by stating 'costs are not calculated'. It stops short of an explicit when-not-to-use statement, but the input-selection condition is unambiguous.

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

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