Generate 90-Character Google Ads Descriptions with AI

Google Ads description lines have a hard 90-character limit, and hitting that limit without wasting a single character is harder than it sounds. You need to pack in a benefit, a differentiator, and a call to action while staying under the cap. Most copywriters write long, then cut. Most cuts kill the best part of the line. That is the problem you are trying to solve right now.

AI description generators solve this by drafting directly to length. You give the model your product, your angle, and your audience, and it returns lines that are already formatted for the 90-character slot. No trimming, no awkward truncations at character 91 that Google silently cuts mid-word.

This page shows you exactly what prompt to feed an AI model, compares outputs from four different models side by side, and explains what separates a description that drives clicks from one that just fills space. If you have an ad group to build or a campaign launching this week, you are in the right place.

When to use this

This approach works best when you have a defined product or offer and need multiple description variations fast. It is ideal for PPC managers building ad groups at scale, founders writing their first Search campaign, and e-commerce teams refreshing seasonal copy without hiring an agency.

• Building a new Search campaign and need 3-5 description variants per ad group for A/B testing
• Refreshing stale ad copy that has run for 90 days or more without a CTR improvement
• Scaling to 20+ ad groups and writing descriptions manually would take a full day
• You have a specific promotion or deadline and need copy that fits the 90-character slot on the first draft
• You are testing messaging angles (price vs. quality vs. speed) and want parallel versions at the same character length

When this format breaks down

• Your offer is highly regulated (legal, financial, pharma) and every word requires compliance review before use. AI drafts will still need a human compliance pass and may introduce disallowed language.
• You have zero context to give the model. If you cannot describe the product, the audience, or the value proposition in a sentence, the output will be generic and useless.
• You need descriptions that reference real-time pricing or live inventory data. AI models do not pull live data, so any figure in the output needs manual verification before the ad goes live.
• Your brand voice is so tightly defined that every word must match a specific style guide. Raw AI output will need heavy editing and may end up slower than writing from scratch.

What makes these work

1. 01
   State the character limit explicitly

   Always write '90-character Google Ads description' in your prompt, not just 'short description.' Models default to their own interpretation of short. Naming the exact limit forces the output into the right slot and reduces editing time significantly.

2. 02
   Give one specific USP, not three

   Descriptions that try to mention price, quality, speed, and a CTA all at once read like a list and convert poorly. Tell the model the single strongest reason someone should click. A focused description with one clear hook consistently outperforms a list of features in A/B tests.

3. 03
   Ask for multiple variants with different angles

   Prompt the model to write three versions: one leading with a benefit, one leading with urgency, one leading with a question. You get testable variation in a single generation, which covers the A/B testing Google RSA rotation requires.

4. 04
   Always verify the character count before uploading

   AI models count characters imperfectly, especially around punctuation and spaces. Paste every output into a character counter or the Google Ads editor before saving. An 91-character description will get truncated by Google with no warning, cutting off your CTA mid-word.

More example scenarios

Product: a project management app for teams under 20 people. Key benefits: simple setup, no per-seat pricing, built-in time tracking. Target audience: small business owners who are fed up with Asana and Monday complexity. Tone: direct, confident. Write a 90-character Google Ads description.

Simple project management with time tracking built in. No per-seat fees. Start free today. (87 characters) -- Alt: Ditch the complexity. Flat-rate project management your whole team can use from day one. (91 chars, trim one word)

Business: local HVAC company in Phoenix, AZ. Offer: same-day AC repair, $89 diagnostic fee waived with repair. Season: summer. Target: homeowners whose AC broke. Urgency is high. Write a 90-character Google Ads description that leads with speed and the waived fee.

Same-day AC repair in Phoenix. $89 diagnostic fee waived with service. Call now for fast relief.

Product: subscription dog food made from human-grade ingredients. Price point: $65/month for a 25 lb dog. USP: vet-formulated, no fillers, cancel anytime. Audience: dog owners who read ingredient labels. Write a 90-character description that emphasizes quality and flexibility.

Vet-formulated, human-grade dog food delivered monthly. No fillers, no commitment. Cancel anytime.

Service: online tax filing for freelancers and 1099 contractors. USP: automatically imports income from 30+ platforms including Upwork and Fiverr. Price: starts at $39. CTA: file now. Write a 90-character description that speaks directly to the freelancer pain point.

Auto-imports your 1099s from Upwork, Fiverr, and more. File your freelance taxes from $39.

Product: endpoint security software for companies with 50-500 employees. Key claim: blocks 99.9% of ransomware attacks, deploys in under 2 hours, no hardware required. Audience: IT managers worried about ransomware. Write a confident, specific 90-character description.

Block 99.9% of ransomware attacks. Cloud-based endpoint security deploys in under 2 hours.

Common mistakes to avoid

• Skipping the character count check

  Trusting the model's character count without verifying is the most common and most damaging mistake. Google truncates at 90 characters without warning. If your CTA sits at the end, it gets cut and you pay for clicks that never saw a reason to act.

• Prompting without a USP or audience

  Prompts like 'write a Google Ads description for my software company' produce generic output that could apply to any company in any category. The model needs your specific differentiator and the specific person you are targeting. Vague input produces vague copy.

• Using all five description slots with identical angles

  Google RSA rotates descriptions, so filling all five slots with benefit-first copy means you never test urgency or social proof. Treat each slot as a separate test. Different angles give Google the variation it needs to optimize and give you real data on what resonates.

• Ignoring the description's job relative to the headline

  Headlines carry the keyword and the hook. Descriptions should add information the headline cannot fit, like a secondary benefit, a trust signal, or a CTA. Writing descriptions that repeat the headline wastes the slot and produces ads that feel redundant to the user.

• Keeping AI output unchanged without brand review

  AI descriptions sometimes include superlatives like 'best' or 'guaranteed' that Google may flag, or claims your business cannot legally support. Run every output through a one-minute sanity check before the ad goes live. A disapproved ad during a launch week is an expensive mistake.

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