WEM Price Compare

Checks a price someone has claimed for a product against the prices WEM has itself observed at retailers (recent readings, within a small tolerance; not a live quote), and reports the cheapest observed offer. Identify the product by gtin (strongest), slug, wem_id, provider + externalId, or title (weakest, relevance-checked). `retailer` names the shop the claim is about; without it the nearest observed price at any shop is checked. Only offers in the claim's currency are compared. Verdicts: confirmed (WEM observed that price there), price_moved (WEM last observed a different price there), not_at_retailer (WEM has no observed price there, though it may hold a feed price), no_claim (no price given; the offers are returned), unknown_product (the product could not be resolved, or WEM holds no observed price for it in that currency). unknown_product means the claim could not be checked, not that it is false. `lastConfirmedAt` says when WEM last observed a price in the answer, or is null. Each call records an evidence receipt, whose id can be cited later.

verify_offer

Lists the retailer offers WEM's catalogue holds for one product, current prices first and each group cheapest first, with WEM's 90-day price low (null when the product is held only in another currency). The product is found by barcode, catalogue slug or wem3.ai/pl/ URL, WEM ID, or a title (a model name, ASIN, MPN or merchant SKU) that must pass a relevance check; there is no live retailer search. A barcode, slug or WEM ID match is the product itself; a title match is inferred and marked so in `identity`. A marketplace offer priced far below the product's other offers is withheld and counted in `filtered`. When WEM does not hold the product, `found` is false and `nextTool` names search_products with a query.

compare_offers

Lays 2 to 5 listings from earlier search results side by side in `comparison`: each listing's price and currency, and its rating, shipping and features where the retailer source supplies them (many listings carry none). Each item needs the listing's `provider` and its `id` as `product_id`. Listings that cannot be found are left out, and fewer than two found is an error. Prices stay in each listing's own currency.

compare_products

Lists current promotions (sales and offers) that retailers in WEM's Awin affiliate programmes have published, for the shopper's market. Filter by merchant or by words in the offer. Each row gives the offer, its dates and a tracked link. A promotion is not a price, and it is not a discount on a product unless its terms say it covers that product. Checkout codes are shown only where the retailer's programme lets WEM publish them; other matching promotions are counted by reason in `withheld`, and a withheld code may still exist. An empty result covers only these programmes, not every offer a retailer runs.

search_promotions

Searches WEM's partner-feed products by meaning, for a plain-language need such as "comfortable shoes for standing all day" or "gift for a 10 year old who likes science". If the description is a product identifier (a barcode, ASIN, MPN, merchant SKU or wem3.ai/pl URL), that product is looked up instead and the reply takes the keyword-search shape. When no products come back, `reason` says why: `index_empty` means nothing matched; `no_embedding_key`, `no_catalogue_client`, `embedding_failed`, `query_failed` and `timed_out` mean the semantic index could not be searched this time, which says nothing about whether such products exist.

semantic_search

Picks one listing for a kind of product within the shopper's constraints, from WEM's catalogue and a live retailer search (a current catalogue match answers without the live search). Candidates are first filtered to plausible matches, so an accessory, another size, an out-of-stock listing or one priced far below the product's other offers is not picked. With no `priorities`, or with `cheapest` first, the lowest price wins; `best_rated`, `free_shipping` and `fastest` (has a delivery estimate) are weighed in the order given, where listings carry ratings or delivery details, and can outrank a lower price. WEM's commission is not a factor. `recommendation` is null with a reason when nothing matched confidently, when the matches differ in size, or when only stale prices remain; when `coverage.kind` is `marketplace_only` it is null but `alternatives` still lists the listings. `recommendation.verified` is true when WEM has recently observed that price at the retailer.

find_lowest_price

Returns one product's details. Given `provider` and `product_id` from a search result, it returns that listing as its retailer source supplies it (title, price and link, with rating, shipping or features where the source has them); when the source cannot be reached it falls back to WEM's catalogue record of the listing, and an unknown listing is an error. Given `wem_id`, it returns that catalogue product with the retailer offers WEM holds for it.

get_product

Lists the six broad shopping categories WEM covers (electronics, fashion, beauty, home, sports, collectibles), each with example products, the shops WEM has read a price from in the last 14 days (busiest first, with how many shops there are in all) and the default currency (GBP). Use it to help a shopper narrow a vague request. It returns no prices, the category names are labels for the shopper, not filter values, and a shop on the list is not a promise that WEM holds a given product there: compare_offers says which shops WEM has for one product.

get_categories

Fetches an evidence receipt by its id (wem-evr- followed by 32 hex characters), as issued with a verify_offer result. Returns the receipt's fields: verdict, observed_at, source, amount, currency and amount_minor, identity_method, verifier, standardVersion and issuedAt, with `signed` true and an HMAC `signature` when WEM signed it. It holds the citation, not the product's offers. A receipt issued moments ago may not be fetchable yet.

get_evidence_receipt

Looks up to 20 product identifiers in one call: barcodes (EAN/UPC/GTIN), Amazon ASINs, WEM IDs, catalogue slugs or wem3.ai/pl URLs. Each row has a status: found (WEM's catalogue holds it; the row gives its number of retailer offers, the lowest current price at a named retailer in the shopper's currency, a marketplace low where there is one, and a link to WEM's product page), not_found (WEM does not hold it yet, which says nothing about whether it exists or has a price), unrecognised (not an identifier, such as a product name) or not_checked (not reached in this call, so not a miss). Identifiers beyond 20 are counted in `overLimit`.

lookup_products