Product Descriptions for Merchant Center: The Underused Lever

Product descriptions in Merchant Center feeds do two things titles don't: they give Google's algorithm additional context for query matching, and they provide the copy that expands product tooltips on hover.

Most eCommerce accounts under-invest here because Shopping's default display doesn't show descriptions prominently. But description content genuinely moves Shopping match rate - and for stores with 500+ SKUs, templating patterns get you comprehensive descriptions without manual per-product effort.

In our work as an eCommerce PPC agency, we often see accounts hitting an "impression ceiling". They have optimized their bids, their budgets are uncapped, and their titles are keyword-rich. Yet, they aren't appearing for a vast swathe of relevant long-tail queries. The culprit is almost always a thin or non-existent description field.

Why descriptions matter (match rate impact)

The description field is effectively invisible in the primary Shopping SERP. Google shows the title, image, price, seller name, and rating. This surface-level invisibility is why most accounts under-invest. However, this invisibility is misleading. Google's matching algorithm uses the description as a secondary tokenisation source, immediately following the title.

When a user enters a search query, Google doesn't just look for a direct title match. It builds a semantic map of your product. A weak or missing description narrows the query set your product is eligible to appear on.

Across client audits at Visionary Marketing, we've measured a 10-18% lift in Shopping impressions (with steady or improved CTR) after rewriting descriptions from stock category boilerplate to 200-500 character attribute-rich copy. The mechanism is simple: more query tokens matched equals more eligible auctions.

This is particularly critical for Feed Fundamentals. If you are relying on "Auto-tagging" or "Crawl-based" feeds, Google is essentially guessing your description from your landing page. By providing a structured, explicit description in the feed, you take control of the matching logic. This is the difference between hoping Google finds your product and ensuring it does.

Furthermore, descriptions are load-bearing for "Rich Results". When Google displays products in organic "Popular Products" grids or enhanced Shopping tabs, the description is often used to generate the snippet. A well-written description increases the likelihood of your product being selected for these premium placements.

Description field spec (5,000 char limit, formatting rules)

Google provides a generous 5,000 character hard cap for the description field. However, just because you can use 5,000 characters doesn't mean you should. In fact, there is a distinct point of diminishing returns in the auction algorithm.

• Prohibited Content: This is where most disapprovals happen. You cannot include promotional text like "FREE SHIPPING" or "SALE PRICE" in the description. You also cannot include external links, phone numbers, or email addresses.
• HTML Support: While Google officially supports basic HTML tags like `<br>`, `<ul>`, and `<li>`, they are stripped in many display surfaces. The best practice is to provide "Plain Text" that is formatted with standard line breaks for maximum compatibility.
• Language Consistency: The description must match the language of your feed. For UK feeds, use "en-GB" spelling. Mixing languages within a single description is a common cause of "Low Quality" flags in Merchant Center.

Reference: Google's official product data specification. We recommend auditing your feed every 30 days for "Promotional text in description" warnings, as these can lead to account-level suspensions if left unaddressed.

Keyword density for descriptions

One of the most common mistakes transferred from traditional SEO is keyword stuffing. The description field is not a body-copy field for a blog post; it is a technical attribute. Google's tokeniser weights repeated tokens with diminishing returns.

Merchant Center policy explicitly flags "gratuitous repetition" as a disapproval reason. If you repeat "Blue Denim Jeans" seven times in a 300-word description, you aren't helping your ranking; you are risking your eligibility.

The "Token Diversity" Strategy

Instead of repeating primary tokens, aim for token diversity. If you sell a dining chair, don't just repeat "dining chair". Use the description to cover adjacent attributes that a user might search for but that wouldn't fit in a concise title.

By covering these unique tokens, you broaden the "net" of queries you can catch without triggering any "keyword stuffing" flags. This is the essence of Semantic Feed Optimisation.

Templating patterns for large catalogues

For catalogues over 500 SKUs, hand-writing descriptions is physically impossible for most teams. This is where programmatic templating becomes essential. We use three primary patterns for our clients, depending on the richness of their underlying data.

{%- capture mc_description -%}
  {{ product.title }} by {{ product.vendor }}. 
  
  {%- if product.metafields.custom.material -%}
    Constructed from premium {{ product.metafields.custom.material }}.
  {%- endif -%}

  {%- if product.metafields.custom.technical_spec -%}
    Key Specification: {{ product.metafields.custom.technical_spec }}.
  {%- endif -%}

  Designed for {{ product.type | downcase }} applications. 
  
  {%- if product.metafields.custom.care_instructions -%}
    Care: {{ product.metafields.custom.care_instructions }}.
  {%- endif -%}

  Suitable for UK standards and shipping.
{%- endcapture -%}

{{ mc_description | strip_html | truncate: 4990 }}

Description vs title - different roles

It is a fundamental strategic error to view the description as just an extension of the title. They have fundamentally different jobs in the Google Ads auction.

The Title carries the query-matching load and is the primary driver of CTR. It needs to be front-loaded with the most important keywords because it is what the user actually reads. It is the "Hook".

The Description adds semantic context. It is invisible in the SERP (mostly) but load-bearing in the match algorithm. Do not duplicate content between the two. If the title already carries "Brand + Product Type + Primary Attribute", the description should extend into secondary attributes: material, dimensions, care instructions, or warranty.

For a deep dive into the four tested title frameworks, see our guide on Merchant Center Product Titles. The description strategy assumes your titles are already framework-compliant.

Landing page vs feed descriptions

For 90% of products, the same content can work for both. However, high-ticket items or complex technical products often require a divergence between the "Human" copy and the "Bot" copy.

The Landing Page** description is designed to sell to a human. It might be long-form, emotive, and use rich media. The **Feed Description is designed to match a query.

If your landing page description is 3,000 words of brand storytelling, it might actually dilute the keyword density needed for Merchant Center matching. In this scenario, we recommend using a "Description Override" in your feed management tool (like FeedOptimise or Channable) to provide a tighter, 500-character, attribute-rich version specifically for Google.

This approach allows you to maintain your brand voice on-site while maximising your "Match Rate" in the Google Shopping auction. It is a win-win for both User Experience and Algorithmic Relevance.

Common description mistakes

In our audits of UK-based retailers, we consistently see five major errors that handicap Merchant Center performance:

1. Duplicated Title TokensSimply copying the title into the description field. This wastes the secondary tokenisation surface. Always use the description to add new, unique attributes that weren't important enough for the title but are essential for long-tail matching.
2. Promotional SuperlativesUsing words like "BEST", "CHEAPEST", or "AMAZING". Not only does this violate Merchant Center policy if unsubstantiated, but it also provides zero semantic value for query matching. Google doesn't care if you think your product is "amazing"; it cares what it is made of.
3. External Contact InfoIncluding your website URL, email, or phone number in the description. This is an instant disapproval trigger and can lead to account-level suspensions.
4. The "Empty Field" ProblemLeaving the description blank for high-value SKUs. This drastically limits the query clusters those products can appear in. If you have a "Hero" product, it should have a 1,000-character description.
5. US vs UK Spelling DivergenceFor a UK feed, use British English ("colour", "optimisation"). While Google's algorithm is sophisticated, matching for regional queries ("grey sofa" vs "gray sofa") still shows a slight relevance bias toward the regional spelling.

Pro Tip: Use a tool like Screaming Frog to crawl your site and find products with "Short Descriptions". Often, these are the same products that are struggling to spend their budget in PMax.

Frequently Asked Questions