SerpApi has added another structured surface over a page that was never built to be one. In How to scrape eBay Seller API for product catalogs, feedback, and promos, the post describes an API that “turns any eBay store or user profile into clean, structured JSON”: seller results with username, bio, items sold and a positive feedback percentage, paginated product results with prices and listing types, auction fields such as bid count and time remaining, and, for user sellers, a feedback breakdown and buyer comments. Each product carries a link into SerpApi’s eBay Product API for the detail page. The reason given is the familiar one: eBay “aggressively blocks suspicious IPs, serves CAPTCHAs, enforces rate limits, and frequently changes its page markup.”
There are no usage figures, only the free tier, 250 searches a month, and a Ruby example that walks five pages at 72 items each. Two details are better than most tutorials. The required type parameter forces the caller to know whether a seller is a store or a user before asking, and the post gives three ways to tell, starting with whether the eBay URL uses /str/ or /usr/. And the key handling advice is specific: the key “grants full access to your search quota, so treat it like a password,” it can be rotated instantly, and “the old key stops working immediately.” What the post does not discuss is eBay, whose own public APIs cover much of the same seller and listing data under eBay’s terms; this is a scraping product, and it says so in the title.
The catalog holds SerpApi as a provider with a thin contract. The SerpApi provider page lists 7 API pages, the SerpApi Search API that every engine including this one routes through, the Google Search, Maps, Local, Jobs and Trends APIs, and the SerpApi Account API that reports the quota the post tells readers to guard. The eBay Seller API has no page. The agentic access profile maps 3 operations. On the Agent Readiness score, the MCP server, agent skills, auth clarity and the rate limit signal are lit.
The Kin Score is 31.7, thin band, with discoverability at 60.0 and contract quality at 44.7 against operational transparency at 13.2 and contract governance at 0.0. The Agent Readiness score is 30.7. The shape is the one this series keeps finding on API products built over other people’s pages: a broad, fast-moving catalog of engines described in documentation, and a published contract that names one generic search endpoint with an engine parameter. That keeps the contract small and the product flexible. It also means an agent reading the contract learns there is a search endpoint, and has to read the blog to learn there is an eBay seller behind it.