Use CompSniper with ChatGPT, Claude or Cursor
A copy-paste setup prompt that teaches ChatGPT, Claude, Cursor or any AI assistant to build with the CompSniper sold-comps API, plus the agent skill and MCP options.
There are two ways to put CompSniper in an AI assistant. Pick the one that matches what you want.
| You want to | Use |
|---|---|
| Have the assistant write code that calls the API (a script, a sheet, an app) | The setup prompt below, or the agent skill |
| Ask for sold prices in the chat, no code | The MCP connector, no API key needed |
1. Save your API key
Create a key in the dashboard and save it as an environment variable named
COMPSNIPER_API_KEY. Do not paste the key into the chat: the prompt tells the assistant to read it from
the environment instead.
export COMPSNIPER_API_KEY="cs_live_REPLACEWITHYOURKEY"2. Paste the setup prompt
Copy this into ChatGPT, Claude, Cursor, Codex or any other assistant, then describe what you want to build.
You are helping me build with the CompSniper API, which returns real completed (sold) eBay listings and other marketplace data as JSON.
Read these before writing code:
- Agent skill (endpoints, parameters, errors, billing): https://compsniper.com/.well-known/skills/compsniper/SKILL.md
- Full reference: https://compsniper.com/.well-known/skills/compsniper/references/api-reference.md
- All docs as plain text: https://compsniper.com/llms.txt
Rules:
- Base URL: https://api.compsniper.com
- Auth: send the header "Authorization: Bearer <key>". Read the key from the COMPSNIPER_API_KEY environment variable. Never hardcode it, print it, or put it in browser code.
- Sold comps: GET /v1/scrape?keyword=...&sold=true&ebaySite=ebay.com (up to 240 sales per call, with a summary block: median, mean, p25, p75).
- Older sales: GET /v1/research/sold returns up to 3 years of eBay sold history (startDate and endDate required, 50 rows per page, follow nextPage).
- Trading cards: GET /v1/tcgplayer/sold takes a product name or productId, never a pasted eBay title.
- Keep keywords short: brand plus model, or card name plus set and number. Extra words remove matches.
- On 429 or 503, wait for the Retry-After header and retry a bounded number of times. Do not retry 400 or quota_exceeded. Failed requests are not charged.
Start with a short script that prints the median sold price and sample size for "nintendo switch oled", then ask me what to build next.The same prompt is one click away in your dashboard, under Use your key with ChatGPT, Claude or Cursor, right after you create a key.
3. Keep the assistant on track
- Point it at the skill. If your tool supports Agent Skills (Claude Code, Cursor, Codex), install the
CompSniper skill once with
npx skills add https://compsniper.comand skip the prompt. - Short keywords win. Assistants tend to send full product titles. Ask for brand plus model, or card name plus set and number. See Getting more results.
- Failed requests are free, so a bounded retry on
429or503costs nothing. See Errors.