{
  "id": "N01-BAG",
  "url": "https://cartforagents.com/guides/travel-bag-field-guide",
  "title": "Travel bag field guide: check capacity, dimensions and airline fit before you recommend a bag",
  "description": "What a shopping assistant or careful traveller should check before recommending a travel bag: the trip and airline, outside dimensions in the state the bag will fly, how capacity was counted, and when to say \"not enough information\".",
  "answer": "Before recommending a travel bag, ask which airline and fare, whether the bag goes overhead or under the seat, the travel date, and what has to fit inside. Compare the bag's labelled outside dimensions, in the state it will fly, against that airline's current limit, and check that the dimensions and the litres can both be true. If a listing only says \"carry-on compliant\", say you can't confirm it fits and ask for the measurements.",
  "take": "Every 40-litre bag in our search claimed to work as a carry-on, and only three printed their outside dimensions in their description. \"Carry-on\" is a claim; the dimensions and the airline's page are the evidence.",
  "summary": "A checklist for anyone recommending a carry-on or under-seat bag, human or AI. Start from the trip, compare outside dimensions in the state the bag will fly, treat \"carry-on compliant\" as a claim to check, and do the arithmetic. With real examples from Shopify's catalog.",
  "claims": [
    {
      "text": "For the search \"40L carry on travel backpack\", all 10 descriptions described the bag as carry-on, airline-ready or similar. One named any airline. Three gave the bag's outside dimensions in the description (positions 7, 8 and 10); Shopify's generated spec lists gave dimensions for two more (positions 4 and 9).",
      "source_title": "Cart for Agents: Travel bag field guide, How we checked",
      "source_url": "https://cartforagents.com/guides/travel-bag-field-guide#how-we-checked",
      "source_date": "2026-11-04",
      "method": "observed",
      "limitation": "One unpersonalized search, top 10. Counts what was written, not whether any bag fits any airline's limit."
    },
    {
      "text": "In the same search, six 40-litre listings described how much they hold in days of clothing, including \"2–3 days\" (main compartment), \"3-5 days\" (at maximum capacity), \"5–7 days\", \"7-10 days\" and \"1–2 weeks\".",
      "source_title": "Cart for Agents: Travel bag field guide, How we checked",
      "source_url": "https://cartforagents.com/guides/travel-bag-field-guide#how-we-checked",
      "source_date": "2026-11-04",
      "method": "observed",
      "limitation": "Quotes listing copy. Packing styles differ; we didn't pack any bag."
    },
    {
      "text": "The listing in 1st place described an expandable design \"with 25L-40L of travel backpack storage space\". Shopify's generated spec list said \"Maximum Capacity: 40L (expandable to 25L)\".",
      "source_title": "Cart for Agents: Travel bag field guide, How we checked",
      "source_url": "https://cartforagents.com/guides/travel-bag-field-guide#how-we-checked",
      "source_date": "2026-11-04",
      "method": "observed",
      "limitation": "We can't see how Shopify generated the field."
    },
    {
      "text": "For the search \"personal item backpack that fits under airline seat\", the listing in 10th place said it measured \"40 × 30 × 20 cm\", was \"+5 cm expandable\", offered \"45L capacity via vacuum compression\", and qualified as a free personal item on several named airlines. 40 × 30 × 20 cm is a box of 24 litres.",
      "source_title": "Cart for Agents: Travel bag field guide, How we checked",
      "source_url": "https://cartforagents.com/guides/travel-bag-field-guide#how-we-checked",
      "source_date": "2026-11-04",
      "method": "inferred",
      "limitation": "Arithmetic on the stated dimensions. We didn't check the named airlines' limits or measure the bag."
    },
    {
      "text": "For the search \"carry on backpack 55 x 40 x 20 cm\", the roll-top listing in 3rd place gave three sets of dimensions: 45 x 30 x 15 cm, \"Rolls down to 40 x 30 x 15 cm (cabin-size compatible)\" and \"Expands to 55 x 30 x 15 cm\". Shopify's generated spec list gave \"45 x 30 x 15 cm (20L)\" and dimensions for a 30 L size, without the rolled or expanded states.",
      "source_title": "Cart for Agents: Travel bag field guide, How we checked",
      "source_url": "https://cartforagents.com/guides/travel-bag-field-guide#how-we-checked",
      "source_date": "2026-11-04",
      "method": "observed",
      "limitation": "Quotes one record. We didn't measure the bag."
    },
    {
      "text": "For the search \"anti theft backpack for city travel\", the listing in 8th place said \"Volume: 28L\", \"Height: 11.2 inch\", \"Width: 7.5 inch\" and \"Depth: 2.4lbs\" in its description. Shopify's generated spec list gave \"Depth 2.4 in\" and \"Weight: 2.4 lbs (1.1 kg)\". 11.2 x 7.5 x 2.4 in is about 3.3 litres.",
      "source_title": "Cart for Agents: Travel product data",
      "source_url": "https://cartforagents.com/guides/travel-product-data",
      "source_date": "2026-10-26",
      "method": "observed",
      "limitation": "One saved snapshot. The volume figure is our arithmetic; a soft bag isn't a box."
    },
    {
      "text": "Shopify marks some Global Catalog fields as Inferred, generated or enriched by Shopify, including the description, options, technical specifications, top features and unique selling points. It says they may not always be present, may vary in accuracy, and should be treated as discovery signals rather than merchant-authored source text.",
      "source_title": "Shopify: Global Catalog MCP, Inferred response fields",
      "source_url": "https://shopify.dev/docs/agents/catalog/global-catalog",
      "source_date": "2026-11-04",
      "method": "documented",
      "limitation": "Living developer documentation. It doesn't say which values were generated for a given product."
    }
  ],
  "sources": [
    {
      "title": "Shopify: Global Catalog MCP",
      "url": "https://shopify.dev/docs/agents/catalog/global-catalog",
      "accessed": "2026-11-04"
    },
    {
      "title": "Cart for Agents: Travel product data",
      "url": "https://cartforagents.com/guides/travel-product-data",
      "accessed": "2026-11-04"
    }
  ],
  "limitations": [
    "This checklist recommends no product, brand or airline. It doesn't say whether any bag meets any airline's rules; only the airline's current page and the gate agent can.",
    "We haven't tested whether shopping assistants that follow this checklist give better answers.",
    "The examples come from Shopify Catalog searches on October 26 and November 4, 2026, top 10 results, with no shopper location set. A search today could look different.",
    "Box-volume checks are rough: a soft bag isn't a box, so they catch impossible numbers, not small errors.",
    "We wrote the searches to sound like travellers. Store and brand names are withheld. The worked example near the end uses invented listings."
  ],
  "related": [
    "https://cartforagents.com/guides/travel-product-data",
    "https://cartforagents.com/guides/spec-sold-product-guides",
    "https://cartforagents.com/guides/product-claim-provenance",
    "https://cartforagents.com/guides/product-specification-template",
    "https://cartforagents.com/research/ai-product-data-unit-normalization",
    "https://cartforagents.com/guides/humidifier-field-guide",
    "https://cartforagents.com/guides/winter-outerwear-field-guide"
  ],
  "published": "2026-11-04",
  "updated": "2026-11-04",
  "checked": "2026-11-04",
  "kind": "field-guide"
}