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mcp-price-tracker

Ask your assistant what something costs right now. Point it at any product page and it reads the price off the page, remembers it, and tells you next time whether the price moved, how far, and whether it reached the number you were waiting for. It works on ordinary shop pages by reading the structured data most stores already publish (JSON-LD, Open Graph, microdata) and falling back to the visible price when they do not. When a large retailer blocks automated requests it says so plainly and lets you record the price yourself so the history stays intact. Everything is stored in a JSON file on your own machine.

Built by theluckystrike.

price-tracker demo

Watch any product page for price drops from chat -- no scraping service, no account, all local.

60-second install

npm publish for @theluckystrike/mcp-price-tracker is pending. Until then, the .mcpb one-click bundle or a clone+build is the working path -- both are verified below.

One-click (.mcpb): download price-tracker.mcpb from the latest release and double-click it in Claude Desktop: https://github.com/theluckystrike/mcp-servers/releases/latest

Claude Desktop (claude_desktop_config.json):

{
  "mcpServers": {
    "price-tracker": {
      "command": "npx",
      "args": ["-y", "@theluckystrike/mcp-price-tracker"]
    }
  }
}

Claude Code:

claude mcp add price-tracker -- npx -y @theluckystrike/mcp-price-tracker

Cursor (.cursor/mcp.json):

{
  "mcpServers": {
    "price-tracker": {
      "command": "npx",
      "args": ["-y", "@theluckystrike/mcp-price-tracker"]
    }
  }
}

The npx form above starts working the moment the package is published. Until then, use the .mcpb bundle above, or build from source with exactly these three commands:

git clone https://github.com/theluckystrike/mcp-servers.git && cd mcp-servers
npm install
npm run build -w packages/mcp-license -w servers/price-tracker

Then point your client's command at node with one arg: the absolute path to servers/price-tracker/dist/index.js.

To run in Pro mode set MCP_LICENSE_KEY in the same config block, or call license_activate once with your key.

Tools

Tool What it does
price_check Fetch a page now; returns price, currency, title, extraction confidence and the change against the last stored observation for that URL. No watch needed.
watch_add Start tracking a URL. Stores the first observation. Optional label, target_price, currency.
watch_list Every watch with current price, min, max, change, target, confidence and source.
watch_remove Stop tracking, by id or url.
watch_refresh Re-fetch one watch (id) or all of them (all: true); appends observations and returns current, previous, min, max, change % and target-hit flags. This is the only thing that checks prices.
price_history Stored observations for one watch, oldest first, optional limit.
price_add_manual Record a price you read yourself, for shops that block bots. Creates the watch if needed.
alerts_pending Watches whose latest price is at or below target, or which dropped 5% or more since the previous observation. Free.
license_status Free or Pro, and where to upgrade.
license_activate Activate a Pro key. Verified offline.

Resource: prices://watches - JSON of every watch with its latest price.

Prompt: check_prices - refreshes every watch and summarises the drops and target hits in one command.

What you can say

You say Tool
"What does this cost right now: <url>?" price_check
"Watch that page and alert me if it goes under 40." watch_add
"Show me everything I'm watching and whether anything dropped." watch_refresh (all) then watch_list
"Stop tracking that laptop, I bought it elsewhere." watch_remove
"Refresh my watches." watch_refresh
"What's the price history on the bookshelf I'm watching?" price_history
"I checked myself, it's 39.99 GBP in-store, log that." price_add_manual
"Has anything I'm watching hit its target or dropped a lot?" alerts_pending
"Am I on the free plan or Pro?" license_status
"Here's my license key, activate it." license_activate

Worked example

A real run against books.toscrape.com, from docs/USER_VALUE_R2.md, with WebFetch/WebSearch disallowed so the price-tracker's own tools had to answer:

You: What does this cost right now: https://books.toscrape.com/catalogue/...?

  price_check { url: "https://books.toscrape.com/catalogue/..." }
  -> price 51.77, currency GBP, source regex-fallback, confidence low

Assistant: GBP 51.77. Confidence: low (regex-fallback) -- this page has no
structured price data, so I read it from the visible text.

The confidence label is not decoration: books.toscrape.com carries no JSON-LD or microdata, so this is the one case in testing where the regex fallback was the only path to a number, and the model relayed the "low" label to the user unprompted rather than stating 51.77 as a fact.

Alerts: nothing runs in the background

There is no scheduler and no daemon. A watch is a stored history, not a subscription: prices are re-read only when watch_refresh runs, and alerts_pending reports on what is already stored. The working pattern is to say "refresh my watches" at the start of a session (or run the check_prices prompt), then ask what dropped.

Free vs Pro

Free Pro ($19 one-time)
price_check Unlimited Unlimited
alerts_pending Yes, unlimited Yes, unlimited
Watches 3 Unlimited
History per watch Last 30 observations Full history
watch_refresh one item Yes Yes
watch_refresh all at once No Yes
price_add_manual Yes Yes
Redirect check and extraction confidence Yes Yes

Get Pro - $19 for this server, $39 for every server, lifetime.

How prices are read

In order: JSON-LD Product/Offer (price, priceCurrency, lowPrice), microdata itemprop="price", Open Graph og:price:amount / product:price:amount, meta itemprop, data-price attributes, common price class and id hints (including Amazon's a-offscreen), and finally a regex over the visible text of the first 200 KB. European and US separators are both understood, so 1.299,00 EUR and 1,299.00 USD both become 1299.00.

Prices are stored as decimal strings in the major unit with a . decimal separator and no grouping, for example "1299.00". Timestamps are ISO 8601 UTC.

Every reading carries a confidence: high for JSON-LD, microdata, meta itemprop and Open Graph; medium for data-price attributes and price class or id hints; low for the regex fallback. A low reading on a page with no product title is reported but never stored.

Pages are fetched with a desktop browser User-Agent, a 12 second timeout, redirects followed, and a 2 MB body cap. After the fetch the final URL is compared with the one you asked for: if the shop redirected off the product path - a different path depth, a category or home page, or a generic title such as "Products", "Home", the shop name alone, or "not found" - you get the shop redirected to <finalUrl>, which is not a product page instead of the cheapest item on the listing it landed on. A redirect that only inserts a canonical slug in front of the same product id or path (Newegg, Amazon /dp/, Zalando-style URLs) is accepted, not refused.

How it stores data

Watches and their price history live in one JSON file: ${XDG_DATA_HOME:-~/.local/share}/mcp-servers/price-tracker/watches.json. Every mutation (watch_add, watch_remove, watch_refresh, price_add_manual) happens under an advisory lock file, .../price-tracker/.lock, held across the load-mutate-save cycle so two refreshes running at once cannot interleave. price_check and read-only tools do not need the lock. Saves write to a temporary file and rename it into place, so an interrupted write cannot leave a half-written file. To back up your watch history, copy watches.json.

Limits and honest caveats

Troubleshooting

Privacy

All data stays local, in ${XDG_DATA_HOME:-~/.local/share}/mcp-servers/price-tracker/watches.json. The only network requests are to the product pages you name. License keys verify offline; nothing is sent anywhere.

Pairs with

FAQ

Why didn't it check the price automatically overnight? There is no scheduler in this server. Prices are only re-read when watch_refresh runs, which happens when you ask for it (or when a cron/launchd job you set up yourself calls it).

Why does it refuse to give me a price on some pages? Either the shop returned a bot-wall response (403) or the request redirected off the product page onto a listing, category or home page. Both are reported honestly instead of returning a wrong number; use price_add_manual to keep the history going by hand.

What does "confidence: low" mean? The price came from a text-pattern fallback rather than the page's own structured data (JSON-LD, microdata, Open Graph). It is usually right but has not been verified against a machine-readable field.

Can I track a price in a currency different from what the page shows? watch_add and price_add_manual accept an explicit currency, but the number you store should match what you actually read -- the server does not convert currencies.

Does it ever send my watch list anywhere? No. The only outbound requests are to the product URLs you add, to fetch their pages. There is no telemetry and no account.

MIT licensed.

Guides

How to track billable hours inside Claude Code and Cursor · Create an invoice PDF from a chat message with an MCP server · Ask questions about an Excel or CSV file from Cursor or Claude · Watch a product price with Claude and get told when it drops · What the free tier includes and what Pro adds · Log expenses and mileage in Claude, split VAT, rebill to an invoice · All guides