Google Ads Character Limits, Compliance, and Why AI Generators Keep Getting It Wrong

Google Ads has a hard constraint that most AI tools pretend doesn't exist: character limits. Headlines max out at 30 characters. Descriptions cap at 90. These aren't suggestions—they're binary.

Why LLMs Can't Count

Large language models don't process text the way humans do. They work with tokens—chunks of text that might be a whole word, a subword, or a single character. When you ask GPT-4 to write a headline under 30 characters, the model understands the instruction conceptually but has no reliable mechanism to count characters during generation.

The Compliance Stack That Actually Works

Reliable ad generation requires a multi-layer validation system that treats the LLM's output as a first draft, not a finished product:

• Layer 1: Prompt optimization - Maximizes first-pass compliance
• Layer 2: Post-generation validation - Programmatic character checks
• Layer 3: Policy filtering - Content policy compliance checks
• Layer 4: Auto-retry - Targeted regeneration of failed outputs

Beyond Character Counts

Character limits get the most attention, but Google Ads compliance is broader. Punctuation restrictions, trademark policies, editorial standards, and claims substantiation all matter.