Marketplace Finder — an MCP server that searches marketplaces in your own browser

One job: let a remote agent (e.g. claude.ai) search online marketplaces for an item — anything for sale, not just housing — through your logged-in browser, running on your machine.

How it fits together

claude.ai  ──HTTPS──▶  tunnel (cloudflared/ngrok)  ──▶  this server (your Mac)
                                                            │
                                                            ▼
                                              your logged-in Chromium (Playwright)
                                                            │
                                                            ▼
                                                   Facebook Marketplace

claude.ai can only reach an MCP server over HTTP, but Facebook Marketplace only shows real results to a real, logged-in browser. So this server runs locally (Streamable-HTTP transport), drives your persistent logged-in Chromium, and you expose it to claude.ai through a tunnel.

The agent gathers missing details from you in chat (budget, city, condition…) before it calls a tool — the tools just declare parameters.

Related MCP server: Chrome MCP Server

Tools the agent gets

• search_facebook_marketplace — query, city, min_price, max_price, radius_km, days_listed, sort (best/newest/price_low/price_high/distance), max_results. Returns structured listings (title, price, location, url, photo, raw text) pulled straight off the results page.

• get_listing_details — full description / condition for one listing URL.

Setup

Just want the full walkthrough? See DEPLOY.md — every step from zero to asking claude.ai to search Marketplace for you (install, login, tunnel, claude.ai connector, daily restart routine, troubleshooting).

python3 -m venv .venv && . .venv/bin/activate
pip install -r requirements.txt
python -m playwright install chromium

python server.py login     # one-time: sign into Facebook, then close the window
python server.py serve      # starts the MCP server on http://localhost:8000/mcp

Then expose it and register it with claude.ai:

cloudflared tunnel --protocol http2 --url http://localhost:8000
#   (or:  ngrok http 8000)

In claude.ai → Settings → Connectors → Add custom connector, paste the tunnel URL with the MCP path:

https://<your-tunnel-host>/mcp

Now ask claude.ai things like "find me a used Herman Miller Aeron under $400 in Seattle, listed this week." It will ask for anything it's missing, then call the search tool, which runs in your browser.

Config (environment variables, all optional)

If MCP_AUTH_TOKEN is unset the endpoint is open — keep your tunnel URL private, or set a token. (claude.ai connectors that support a bearer/OAuth secret can pass it.)

Notes & next steps

• Facebook city slugs are short names like vancouver, seattle, nyc, la, chicago. The agent passes one as city.

• Session expiry: if Facebook starts showing a login wall, the tool says so — re-run python server.py login.

• Adding marketplaces (Craigslist, eBay, Kijiji…): add a new @mcp.tool() in server.py that builds that site's search URL and reuses the same card-extraction pattern. Craigslist needs no login; it's scraped through the same real browser because it blocks datacenter IPs.

• Clarifying questions are handled by the agent today. If you later want the server to drive structured prompts, that's MCP "elicitation" — a tool can request input mid-call via ctx.elicit(...); client support is still uneven.

This folder is self-contained and ready to move into its own repo.