AI Max for Shopping's AI reads your Merchant Center product feed as its primary input for determining auction eligibility and ad relevance. Feed rules — Merchant Center's tool for transforming and supplementing feed data — are a critical lever for AI Max performance. Here's how to use them effectively.
What Feed Rules Are
Feed rules in Merchant Center let you modify product data without changing your source feed. They're transformations applied at ingestion time: you can combine attributes, add prefixes, extract values from one field to populate another, or apply conditional logic.
For AI Max for Shopping, feed rules let you optimize your product data for AI matching without rebuilding your backend feed system.
Title Optimization via Feed Rules
Product title is the most important feed attribute for AI Max query matching. Your existing titles may be optimized for your website's UI (short, branded), but AI Max needs descriptive, specification-rich titles.
Example rule: If your source feed has title: "Blue Widget" and you have separate color, brand, and size attributes, you can create a feed rule that builds a new title: [Brand] [Color] [Product Type] [Size] → "Acme Blue Widget 10cm".
In Merchant Center: Go to Products > Feeds > Rules > Add Rule
- Apply to: Title
- Transformation: Set to value of / Combine values
- Source fields: brand + " " + color + " " + title + " " + size
This lets you keep your website titles unchanged while serving richer titles to AI Max.
Custom Labels for AI Max Campaign Segmentation
Custom labels (0-4) don't affect auction eligibility directly, but they're the tool for campaign segmentation in AI Max for Shopping. Use feed rules to populate custom labels based on product attributes:
Margin tier:
- If price > 200: custom_label_0 = "high-margin"
- If price 50-200: custom_label_0 = "mid-margin"
- If price < 50: custom_label_0 = "low-margin"
Seasonality:
- If product type contains "winter": custom_label_1 = "seasonal-winter"
- If product type contains "summer": custom_label_1 = "seasonal-summer"
Stock level (requires dynamic feed integration):
- If availability = "preorder": custom_label_2 = "preorder"
- If quantity < 5: custom_label_2 = "low-stock"
With these custom labels set via feed rules, you can create separate AI Max for Shopping campaigns for each segment and assign different target ROAS values — high-margin products get aggressive ROAS targets, low-margin products get conservative targets.
Supplemental Feeds for AI Max
Supplemental feeds let you add or override attributes for specific products without modifying the main feed. For AI Max for Shopping, supplemental feeds are useful for:
Adding attributes your main feed doesn't include: If your main feed doesn't include product_highlight attributes (short bullet points about key features), you can add them via supplemental feed. AI Max uses product highlights in ad content.
Seasonal sale prices: Add sale_price and sale_price_effective_date via supplemental feed for promotional periods without touching your main pricing system.
AI Max-specific title overrides: If you want different titles for AI Max Shopping vs. other shopping surfaces, you can't segment by campaign in the feed — but you can create a separate feed with AI Max-optimized titles and use it for a Merchant Center sub-account linked to your AI Max campaign.
GTIN and MPN Accuracy for AI Max
AI Max for Shopping can access Google's product knowledge graph — structured data Google has about products from manufacturers, reviews, and other sources. Products matched via GTIN/MPN to the knowledge graph receive:
- Richer product data (aggregated reviews, product images from multiple sources)
- Higher auction eligibility (Google can confirm the product exists and has consistent data)
- Better query matching (the AI knows what the product is beyond just your feed description)
Feed rule for GTIN completeness: Check your feed for products missing GTINs. For branded products that have UPCs/EANs, add them — even if you need to manually create a supplemental feed mapping your SKUs to GTINs. This is high-effort but high-reward for AI Max.
The June 2026 Deletion and Feed Versioning
The June 2026 data deletion (https://yositeup.com/blog/google-ads-reporting-data-deleted-june-2026) deleted Google Ads conversion data but didn't delete your Merchant Center feed history. However, if you made feed rule changes during the deleted period, you can't see the conversion impact of those changes in Google Ads.
Merchant Center's "Products" history does show when product data changed — check the change log if you made feed rule changes during this period to understand what was live when.
Feed Rules After DSA to AI Max Migration
The DSA migration to AI Max for Search (https://yositeup.com/blog/google-ads-dsa-ai-max-migration-february-2027) doesn't involve feed rules (that's a Search campaign, not Shopping). But if you ran both DSA for Search and PMax (now AI Max for Shopping), your Shopping feed rules from PMax are carried forward unchanged. Audit them: PMax feed optimizations may need updating for AI Max's more aggressive query expansion (titles that were adequate for PMax may need to be more specific for AI Max).
The July 2026 ToS and Feed Content Requirements
The July 2026 ToS (https://yositeup.com/blog/google-ads-tos-july-2026-ai-automation-what-changed) requires that product data in AI Max for Shopping campaigns reflects the actual product being sold. Feed rules that generate misleading titles or descriptions violate this requirement. Specific to feed rules:
- Rules that append promotional language ("Best," "Cheapest," "#1") that isn't verifiable are prohibited
- Rules that truncate required disclosures (for regulated products) are prohibited
- Rules that generate titles implying availability when
availability = "out_of_stock"are prohibited
Feed rules must produce accurate output — they're a data transformation tool, not a compliance bypass mechanism.
AI Max for Shopping Performance Max Legacy
When AI Max for Shopping replaced Performance Max (https://yositeup.com/blog/google-ai-max-shopping-replacing-performance-max-2026), feed rules from your PMax Merchant Center account carried forward unchanged. If you had feed rules set up for PMax Shopping, they're already active for AI Max Shopping. Review them in this context: PMax's weaker query expansion may have allowed looser titles; AI Max's stronger expansion makes precise, attribute-rich titles more important.
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