Point ChatGPT, Claude, Cursor or any assistant at CompsAPI and it works with real completed eBay sales, the accepted Best Offer amount included, up to three years back. Two ways in: ask in chat with no code, or have it build against the API.
Connect the hosted MCP server once, then ask your assistant for sold prices in plain language. Nothing to install, no code to write. Works with Claude, Cursor and any client that speaks MCP.
{
"mcpServers": {
"compsapi": {
"url": "https://api.compsapi.com/mcp",
"headers": { "Authorization": "Bearer YOUR_KEY" }
}
}
}One tool, search_sold_listings. Each call counts as one request, the same as the REST API.
Paste a setup prompt into ChatGPT, Claude or Cursor and it writes working code against CompsAPI. The prompt reads your key from an environment variable, so your key never sits in a chat log.
COMPSAPI_KEY in your environment.The setup prompt appears in the dashboard the moment you create a key, with a copy button and a download for the skill file.
An assistant is only as good as the data under it. Point one at the public eBay page and it reads asking prices on negotiated sales, about three months of history, and whatever junk the search returned. CompsAPI hands it the amount a Best Offer sale actually closed at, up to 1,095 days of history, and a trading card layer that parses grade and grader, so the number it quotes back to you is the number something really sold for.
The setup prompt never contains your key. It names an environment variable and tells the assistant to read it from there, and never to print it or put it in browser code. A key pasted into a chat window can end up in that provider's logs, so we built the prompt to avoid it from the start. If you ever need to, rotate a key from the dashboard in one click.
100 free requests a month · every filter on · no card
Get a free key