CardGauge for Claude and ChatGPT

Ask your AI assistant what a sports card or Pokémon card actually sells for. CardGauge answers from completed sales, never asking prices.

Completed sales onlyRead-onlyNo sign-inFree

What it does

Ask about a baseball, basketball, football, hockey, soccer or Pokémon card. CardGauge looks up completed sales from the last 30 days on eBay, Fanatics Collect and TCGplayer, and gives back:

the median sold price, with how many sales it came from and the range
prices by grade (PSA, BGS, SGC and others) where graded copies sold
an honest "no single price" with the reason, when there are too few sales or the sales cover several different cards, plus which cards turned up so you can say which one you have

Asking prices are never counted as sales. Other parallels, lots, autographs and graded copies are kept out of an ungraded price. Every answer links to the full result on cardgauge.com, where you can see the sales behind it.

How to add it

Claude: one tap

CardGauge is listed in Claude's connector directory. Open the listing and tap Connect:

Add CardGauge from Claude's directory →

Or add it by hand, in Claude or ChatGPT, with the connector address:

https://stock-card-api.onrender.com/mcp

Claude, by hand

Open claude.ai (or the Claude app) and go to Settings → Connectors.
Tap Add custom connector.
Name: CardGauge. URL: paste the address above.
Leave sign-in (OAuth) empty. CardGauge needs no account. Tap Add.
In a chat, make sure CardGauge is switched on in the tools menu, then ask about a card. Claude will ask permission the first time; choose Always allow if you don't want to be asked each time.

ChatGPT

In ChatGPT, go to Settings → Apps & Connectors and turn on Developer mode (under Advanced), if your plan offers it.
Choose Create (add a connector), name it CardGauge, paste the address above, and set authentication to None.
Start a chat, add CardGauge from the tools menu, and ask about a card.

ChatGPT's menus change often and custom connectors aren't on every plan. If you can't find these options, use cardgauge.com directly: it gives the same prices.

What to ask

Give the card as exactly as you can: year, brand or set, player or Pokémon, card number, and parallel or grade if you know them.

"What's my 2018 Topps Update Shohei Ohtani #US285 worth?"
"How much does a Base Set Charizard 4/102 sell for ungraded?"
"What do PSA 9 copies of the 1986 Fleer Michael Jordan #57 go for?"
"Is a 1960 Topps Roger Maris worth grading?"
"Price my 2024 Topps Chrome Paul Skenes #USC88 Refractor."

What answers look like

When there's a clear price

Sold for about $X (ungraded, median of N completed sales in the last 30 days, range $low–$high). Graded: PSA 10 about $Y (N sales)… Full result and the sales behind it: cardgauge.com/?q=…

When there isn't

No reliable single price: too few clean sales of this exact card, or the sales cover several different cards. Cards found in the sales: … Ask which one it is and price that.

No guessing. Every number comes from CardGauge's own calculation over completed sales. The assistant is told to repeat the numbers as given and never estimate a price itself. If it gives a figure CardGauge didn't return, check the link.

Details

Tools	price_card: what one card sells for. search_cards: find cards CardGauge has already priced, by player, Pokémon or set. Both read-only.
Sign-in	None. No account, no payment.
Sales window	Completed sales from the last 30 days
Sources	eBay, Fanatics Collect, TCGplayer
Limits	40 lookups per 10 minutes and 300 a day per user
Privacy	CardGauge receives only the card description the assistant sends, never your conversation. Privacy policy

Help

"Couldn't connect" when adding it: check the address is exactly the one above, ending in /mcp, with no space at the end.
The assistant answers without CardGauge: make sure the connector is switched on for that chat, or say "use CardGauge".
"Too many lookups": you've hit the limit above. Wait a few minutes, or use cardgauge.com.
Wrong card: add the card number and set. "2018 Topps Update Ohtani #US285" beats "Ohtani rookie".

Anything else: cardgauge@gmail.com