Market Category Booster reads a product description and walks the marketplace's own category tree, level by level, until it runs out of children. You get every node on the way down — the one the listing form actually asks for.
One description goes in. One node comes back per level, each priced on its own call, until the budget or the tree ends the descent.
Nothing here is provisioned in advance. An agent that can read a 402 discovers the price, pays it and gets its answer inside the same exchange. No operator opens an account first, and no credential outlives the call.
There is no key to request, rotate or leak. A wallet address is the only identity the service records, and it appears for the first time when the payment does.
A caller that has never seen this API learns what a call costs from the API itself. MCP clients read the same facts from the payment_info tool.
Each step is a separate model call over the names of a single level — never the whole tree. That keeps prompts small, and it makes the cost of a request something you can read off the response instead of guessing.
The store's top-level categories are loaded from the taxonomy and offered as the only options.
The chosen node's children become the next set of options. Repeat while children remain.
Every call's tokens are counted. At 14 000 tokens the descent stops and the last match comes back flagged truncated. A deep tree can't turn into an open-ended bill.
One entry per level, each with the store's own category id — remapped to the external code where the marketplace uses one instead of an internal id.
A request is served if it carries a valid payment. Nothing else: nothing to create, no session, no dashboard to log into.
No key, no signup, no invoice. Call the endpoint, get a 402 with the payment requirements, pay $0.048 in USDC and retry with the signed authorization. Your wallet address is your identity.
Point an MCP client at /mcp for three tools: categorize_product, list_stores and payment_info. Payments travel in the request metadata, exactly as they do over REST.
| Endpoint | Auth | Returns |
|---|---|---|
| POST /categorizations | Payment | The product with one match per level |
| GET /categorizations | Wallet address | Your past categorizations |
| POST /mcp | Payment | MCP tools over streamable HTTP |
| POST /a2a | Payment | A2A agent, JSON-RPC 1.0 — card at /.well-known/agent-card.json |
# retry of a 402, now carrying the payment curl -X POST https://$HOST/categorizations \ -H 'PAYMENT-SIGNATURE: <signed authorization>' \ -H 'Content-Type: application/json' \ -d '{"store_id":"amazon.com", "description":"Waterproof hiking boots, Vibram sole"}'
Descriptions are capped at 2,000 characters: the text is repeated in the prompt at every level, so its length is part of the cost.
Pass one of these as store_id. en-US is the Google product taxonomy.
There's nothing to install. The fastest way to know whether this fits your catalog is to categorize one of your own products.
