Google Shopping Agency: Identifiers, Diagnostics and Campaigns in That Order

Updated November 2026 · Written and maintained by the Progression Agency strategy team

Google has to recognize a product before any bid can help it sell. Merchant Center says products with missing or incorrect GTINs may have limited visibility, and products with no unique identifiers may not be eligible for every Shopping program. So a Google Shopping agency starts in the Diagnostics tab and the product data, not in the campaign settings: identifiers, brand and MPN, variants, then images and titles, and only then budgets and bids. Progression’s team is based in New York and manages Shopping for stores across the US on Shopify, BigCommerce, WooCommerce, Magento and custom platforms.

A product line Google could not match

A hypothetical home goods store sells its own private label line next to branded products. The branded products carry the manufacturers’ GTINs. The private label line had GTINs copied from a supplier sheet, and Merchant Center flags them.

The fix is to submit no GTIN for the store brand items and to fill in brand and MPN. A made up identifier is worse than none, because Google says not to guess or make up a value.

Why is a wrong GTIN worse than a missing one?

Because a missing identifier leaves a product hard to classify, while a wrong one tells Google the product is something it is not.

What a Google Shopping agency fixes before it bids

The work runs in a fixed order, because each step makes the next worth doing. Merchant Center account and business settings come first, then Diagnostics, identifiers, variants, images, titles and categories. Campaigns come last.

A bid on a product Google cannot match buys nothing. For programs that cover several ad channels, see ecommerce advertising agency.

• Check the Merchant Center account and business settings.
• Read every Diagnostics issue by product.
• Fix identifiers before anything else in the feed.
• Fix variants, images, titles and categories.
• Build and tune campaigns on clean data.

What is in the Diagnostics tab?

A list of issues found in the product data, shown per product. Images that break Google’s rules do not appear on Google surfaces and are listed there too.

GTIN, brand and MPN triage

Google says products submitted without any unique product identifiers are difficult to classify and may not be eligible for all Shopping programs or features. Products with missing or incorrect GTINs may have limited visibility. The table sorts the common situations.

Store brands and the empty GTIN field

If you are the only seller of a product or it is a store brand, it generally has no GTIN, so you do not need to submit one. Leave the field empty and complete brand and MPN.

Every color and size is its own product

Each product and each variant has its own GTIN. Several products for the same country and language must not share a GTIN and the same variant attributes, which are condition and multipack for all products, and color and size for apparel.

• Never guess a GTIN. If unsure, submit none.
• Check the check digit with the GS1 calculator.
• Keep one GTIN for each variant.
• Use the bundle’s own numbers if the manufacturer made the bundle.

Optimize Google Shopping feed attributes after identifiers

Once identifiers hold up, the rest of the feed gets attention: titles that lead with what a shopper types, product categories, product types and custom labels that give campaigns a structure. Images follow Google’s own rules, which live on product photography services.

One rule belongs here: images that break the rules do not appear on Google surfaces, and they are listed in Diagnostics. See Google’s image_link page for the full rules.

• Lead the title with what a shopper would type.
• Choose the most specific category that fits.
• Use product types and custom labels to split campaigns.
• Check Diagnostics after every feed change.

Why does the title matter so much?

It is often the first thing a shopper reads. A title that starts with the brand’s marketing line wastes the space where the product’s name should be.

Google Shopping management, week to week

Google Shopping ads management services come down to a weekly routine. Search terms are reviewed and negatives added, products are split across campaigns by what they need, bids or targets are adjusted, new products are checked in Diagnostics and out of stock items are handled.

Performance Max is one campaign type the account may use, and this page makes no claim about how it works. The weekly routine is the same whichever type runs.

What does week to week look like for a small catalog?

Shorter lists and fewer campaigns, with the same checks. The routine scales down without changing.

What Google Shopping agencies charge

Google Shopping agencies price management as a monthly fee, and the figure depends on scope. Pricing depends on scope, is subject to change and is set in the written proposal. Ad spend is paid to Google and is separate from the fee.

• Ask what the fee covers and what ad spend is billed separately.
• Ask how many products and campaigns the scope assumes.
• Ask whether feed repair is part of the fee or a project.
• Ask what the monthly report contains.

Any store platform, one Merchant Center

Products reach Merchant Center from Shopify, BigCommerce, WooCommerce, Magento or a custom catalog through a feed or an integration. The plain advice: fix data in the store platform itself, not only in feed rules, so the store and the listing agree.

• Fix identifiers at the source in the store’s product records.
• Use feed rules only for adjustments the store cannot hold.
• Check that the price and stock in the listing match the store.
• Review Diagnostics after every platform update.

For store platforms, see BigCommerce development, WooCommerce development and Magento development.

Why not just fix everything in feed rules?

Because a fix that lives only in the feed disagrees with the store. When the two differ, the shopper finds out at checkout.

When a Google Shopping ads agency is the wrong first step

A Google Shopping ads agency is the wrong first step for a store whose stock data, return policy or shipping settings are not sorted, or whose prices change daily by hand. Those come first.

• Stock data that does not match what is for sale.
• No return policy or shipping settings in place.
• Prices edited by hand every day.
• No one who owns the product records.

Fixing these makes the later work cheaper, and a store that has done so gets more from every dollar of management.

How long do the prerequisites take?

Usually a few weeks, and the campaign work can begin on the products that are ready.

The monthly report you should get

A good report is short and explains itself. It says what was fixed, what is still open and what comes next.

• Diagnostics issues opened and closed.
• Products eligible against products submitted.
• Spend and revenue by product set.
• Search terms added as negatives.
• Next month’s fixes.

Who reads the report?

The store owner and whoever maintains the product data, so the fixes it lists have an owner.

Reading the Diagnostics tab

The Diagnostics section of Merchant Center names an issue per product. It is the fastest way to see which products Google cannot use.

Issues are fixed at the source and then checked again. The agency looks at Diagnostics after each change and does not promise a time for a fix to appear.

Can Diagnostics be wrong?

It reports what it finds in the data. A fix that exists in your store but has not been processed yet may still show an issue.

Titles and categories that match how people search

A product title is read by the shopper and by Google. Putting the product name, the key attribute and the brand where a reader expects them helps both.

• Start with the product name a shopper would type.
• Add the attribute that tells similar products apart.
• Keep brand names where they belong.
• Choose the most specific product category.

Titles are written once for the feed and checked against what customers actually search, using search terms the campaigns have already collected.

Should titles be the same as on the store?

Not always. The feed title can differ from the page title if the page title is written for browsing and the feed title for searching.

Out of stock and price changes

A product that is out of stock should not be paid for. Stock and price in the listing must match the store, or the shopper loses trust at checkout.

• Send stock status from the store, not by hand.
• Pause campaigns for products that cannot ship.
• Match prices between the store and the listing.
• Check Diagnostics after a price change.

Stores with prices that change daily by hand do better by fixing that process before spending more on ads.

Who owns stock data?

Whoever manages the store’s product records. Management of ads can only be as accurate as that data.

Frequently asked questions