For AI agents & LLM builders
Let your agent price things, without guessing
LLMs invent prices when nothing grounds them. Grail gives your agent real eBay sold comps over MCP — one tool call, a median and range back, no scraping and no made-up numbers.
The problem
Agents have no source of price truth
- —A language model will confidently invent a price when nothing grounds it.
- —Scraping eBay inside an agent is brittle, slow, and breaks often.
- —An agent needs a tool-callable endpoint, not an HTML page to parse.
- —You want the agent to answer “what is it worth?” with a real, checkable number.
How it works
From agent to answer in one call
- 01
Connect MCP
Add the Grail MCP server to Claude, Codex, Cursor, or any MCP client. Bearer-key auth, no local install.
- 02
Call search_sold
Your agent calls search_sold("charizard base set") and gets up to 240 real sold listings plus a median and range.
- 03
Answer with proof
The agent quotes a real median and the sample size behind it, not a guess.
Example
A real number in one tool call
search_sold("charizard base set") returned a median of $682.50 across 3 comps with no error. The agent answers with a number it can defend.
Built for the agent loop
MCP-native
A hosted MCP server at /mcp. No local install, bearer-key auth, works with any MCP client.
Structured output
Stable JSON a model can read: median, range, quartiles, and provenance on every row.
Raw or cleaned
Relevance off for a drop-in feed, on to strip accessories and parts before the median.
Honest limits
Rate-limit headers and documented error codes so the agent retries sanely.
More ways to use Grail
Start free — 100 requests a month.
No credit card. Your own key in the dashboard in under a minute.
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