McMaster-Carr Load Cart

Purpose

Load a McMaster-Carr shopping cart — which McMaster calls the "Order" — with one or more parts identified by part number and quantity, then read back what got loaded: each line's product description, stock/availability, unit (or pack) price, extended line total, and the order-level Merchandise subtotal. This is read-only with respect to your account: it adds line items to the current (anonymous) order and stops there. It never logs in, never selects "Continue as Guest", and never submits/places the order.

When to Use

"Add part 91290A115 (qty 5) and 90128A179 (qty 10) to a McMaster cart and tell me the total."
Bulk-loading a BOM / shopping list of McMaster part numbers to get current per-line and subtotal pricing.
Validating that a list of part numbers still resolves to real, in-stock products before someone places the order.
Any "build/load my McMaster order from this list of parts" request that stops short of checkout.

Workflow

McMaster-Carr's cart is the Order page at https://www.mcmaster.com/orders/ (the header link labeled ORDER). The cart is fully usable anonymously — no login is required to load parts or to see pricing; login (or "Continue as Guest") is only needed to actually place the order, which this skill does not do. No anti-bot stealth is required: a bare Browserbase session (no --verified, no --proxies) loads the page and resolves pricing identically to a stealth session. The site is JS-rendered but the accessibility snapshot is rich and reliable.

The single robust way to load parts via automation is the "Paste part numbers and quantities" box, not the line-by-line Part number / Quantity input fields (those do not reliably trigger McMaster's price lookup under synthetic input — see Gotchas).

Open a plain session and navigate to the order page.

sid=$(browse cloud sessions create --keep-alive | node -e "let s='';process.stdin.on('data',c=>s+=c).on('end',()=>process.stdout.write(JSON.parse(s).id))")
export BROWSE_SESSION="$sid"
browse open "https://www.mcmaster.com/orders/" --remote
browse wait load --remote

Confirm the title is Current Order | McMaster-Carr.

Open the bulk-paste box. Snapshot the page and click the button labeled Paste part numbers and quantities.

browse snapshot --remote     # find the "Paste part numbers and quantities" button ref
browse click "@<ref>" --remote
browse wait timeout 1200 --remote

Fill the paste textarea with one part per line, then click ADD. Re-snapshot to get the textarea ref (label Paste part numbers and quantities) and the ADD button ref.
```
browse fill "@<textarea-ref>" "91290A115 5
90128A179 10" --remote
browse click "@<add-button-ref>" --remote
browse wait timeout 3000 --remote
```
Accepted line formats (shown in the box's own placeholder — any may be mixed):
- PARTNUMBER<space>QTY → e.g. 3313N116 2
- PARTNUMBER,QTY → e.g. 65985K502,5
- <free-text> PARTNUMBER QTY <unit> → e.g. Hex nut 95462A029 1 pack
Read back the loaded order. Snapshot again. Each loaded line renders, in order, as:
- an availability banner above the line: Ships today (in stock) or Delivers in 1-3 weeks (non-stock / made-to-order),
- the product name + spec (e.g. Black-Oxide Alloy Steel Socket Head Screw / M3 x 0.5 mm Thread Size, 10 mm Long),
- the part number, the quantity, the unit/pack descriptor (e.g. Packs of 100 each),
- the unit price ($13.23 / Pack) and the extended line total ($66.15),
- a delete line button.
The right rail's Order Summary → Merchandise cell holds the subtotal (e.g. $202.15). Note the ORDER header link gains a numeric badge equal to the line count.
Emit the structured result and stop. Do not log in, do not click Continue as Guest, do not press Send/Save for later/Print. Release the session:
```
browse cloud sessions update "$sid" --status REQUEST_RELEASE
```

Site-Specific Gotchas

"Cart" is called "Order." The cart lives at https://www.mcmaster.com/orders/ and the header link is ORDER (with ORDER HISTORY next to it). There is no "cart" wording anywhere on the page.
No login and no stealth needed. Pricing renders for anonymous users. Verified with both a stealth (--verified --proxies) session and a bare session — pricing was byte-identical (91290A115 → $13.23/Pack in both). The pre-run anti-bot probe reported none detected, consistent with what we saw. Don't waste budget on stealth flags.
Use the Paste box, NOT the line-by-line inputs. Typing a part number + quantity directly into the per-line Part number / Quantity textboxes (via browse fill or browse type+Enter) leaves the text in the field but does not trigger McMaster's product lookup — the line never resolves to a product and the Merchandise subtotal stays unchanged. Verified twice (with Tab and with Enter). The Paste part numbers and quantities box is the only input path that reliably commits and prices lines under automation. The "Build order line by line" toggle just switches back to those flaky inputs.
browse fill accepts multi-line strings for the paste textarea — pass an actual newline-separated string (each part on its own line). The box parses each line independently and is tolerant of mixed formats (space-delimited, comma-delimited, and free-text-with-embedded-part-number all work in one paste).
Non-stock / "Delivers in 1-3 weeks" lines may show -- for price. A part can resolve to a valid product (description + spec render) yet show -- for both unit price and line total, contributing $0 to the Merchandise subtotal — observed for 94639A102 (Off-White Nylon Unthreaded Spacer), which carried a Delivers in 1-3 weeks / Need this sooner? banner instead of Ships today. Treat a line with a resolved description but -- price as a distinct, valid outcome (priced: false), not a failure. The subtotal only reflects priced lines.
Quantity unit is per-pack for pack items. Many McMaster parts sell in packs (Packs of 100 each); the quantity you load is the number of packs, and the line total = quantity × pack price, not × each-price. Report the unit descriptor alongside the quantity so the number isn't misread as "each".
Read-only boundary. Stop at the loaded order. The right rail shows Log in to place an order, Create login, and Continue as Guest — none of these should be clicked. The top toolbar's Send, Save for later, Delete, and Print are also out of scope.
The order is session/cookie-scoped. A freshly created Browserbase session starts with an empty order; loaded lines persist within that session but a brand-new session is empty. There is no "saved cart" to load anonymously — "load cart" here means populate the order, not restore a prior one.
A genuine McMaster API exists but is gated. The footer API link points to McMaster's Product Information / eCommerce API, which requires an approved business account and a mutual-TLS client certificate. It is not usable for ad-hoc agents — the browser Paste flow is the practical path.

Expected Output

{
  "cart_url": "https://www.mcmaster.com/orders/",
  "logged_in": false,
  "line_count": 2,
  "lines": [
    {
      "line": 1,
      "part_number": "91290A115",
      "description": "Black-Oxide Alloy Steel Socket Head Screw M3 x 0.5 mm Thread Size, 10 mm Long",
      "availability": "Ships today",
      "quantity": 5,
      "unit": "Packs of 100 each",
      "unit_price": "$13.23",
      "unit_price_basis": "Pack",
      "line_total": "$66.15",
      "priced": true
    },
    {
      "line": 2,
      "part_number": "90128A179",
      "description": "Zinc-Plated Alloy Steel Socket Head Screw M2 x 0.4 mm Thread, 8 mm Long",
      "availability": "Ships today",
      "quantity": 10,
      "unit": "Packs of 100 each",
      "unit_price": "$13.60",
      "unit_price_basis": "Pack",
      "line_total": "$136.00",
      "priced": true
    }
  ],
  "merchandise_subtotal": "$202.15",
  "note": "Applicable shipping and tax will be added."
}

Distinct outcome shapes:

// A non-stock line that resolves but shows no price (does not add to subtotal)
{
  "line": 1,
  "part_number": "94639A102",
  "description": "Off-White Nylon Unthreaded Spacer 1/4\" OD, 3/16\" Long",
  "availability": "Delivers in 1-3 weeks",
  "quantity": 3,
  "unit": "Packs",
  "unit_price": "--",
  "line_total": "--",
  "priced": false
}

// Mixed order: subtotal reflects only the priced lines
{
  "line_count": 2,
  "lines": [ /* one priced "Ships today" line + one "--" non-stock line */ ],
  "merchandise_subtotal": "$66.15"
}