Automating your brand posts with Gemini

Create a reusable Gemini Skill for branded social captions and images.

Introduction

30 Second Summary

A fresh promotion often means rebuilding the same tone, audience, and visual direction from memory. That repeated setup turns a weekly post into another blank-page task.

In this project, you will save those brand rules as a reusable Skill in Gemini Apps. A short promotion message will then produce three branded captions plus one matching image.

What You'll Build

A fresh chat with a new weekly promotion will return three branded captions plus a matching image without another long brand prompt.

By the end of this project, you'll have:

A reusable social-post Skill that turns one short promotion into three branded captions plus a matching image.
A practical brand-fit check you can use to strengthen each result before publishing.
A fresh-chat demo that produces a second caption set plus another image without rebuilding the brand prompt.
Secret Mission: Add a captions-only mode that turns one promotion into a coordinated three-post campaign sequence.

Are there any prerequisites?

You need a personal Google Account, a web browser, and to be aged 18 or over. The first step confirms that Keep Activity is on and Skills are available in Gemini Apps.

Before We Start

Before the hands-on work begins, lock in the repeated small-business posting task you want to improve. This commitment gives your reusable Gemini Skill a clear purpose.

Compare a One-Off Prompt

Weekly promotions become tedious when every chat begins with the same background. An ordinary chat can only use the details it receives in that conversation.

This step gives Gemini Apps one promotion without any saved brand context. You will compare the result with a business profile you keep outside the prompt.

In this step, get ready to:

Confirm your account has access to Skills.
Record a complete business profile plus your first promotion.
Compare that profile with the result from a one-off prompt.

Confirm your Gemini Apps access

Skills are available to account holders aged 18 or over. Your Gemini Apps session also needs Keep Activity turned on.

In the browser from earlier, go to https://gemini.google.com.
Sign in with your personal Google Account.
Confirm you are aged 18 or over.
Select Settings & help.
Select Activity.
Check the status of Keep Activity.
Turn on Keep Activity if it is disabled.

Why Keep Activity Matters

Gemini Apps requires Keep Activity for creating or using Skills. This setting must be active before the reusable workflow can work.

Return to Gemini Apps.
Select More if Customize is absent from the sidebar.
Select Customize in the sidebar.
Select Skills.
Confirm the Skills page loads.

That clears the account check. Your account now has the settings needed for the rest of the project.

Cannot See Skills?

Confirm you signed in with a personal Google Account.
Confirm you are aged 18 or over.
Return to Activity to confirm Keep Activity is on.
Select More to check whether Customize is hidden.

Help me check why Skills are unavailable in Gemini Apps.

Record your business profile

A business profile gives you a fixed standard for evaluating any generated captions. Specific details make the difference between recognizable brand copy and wording that could belong to anyone.

Choose a real or fictional business for your repeated weekly posts.
Record its name here: your business name.
Record what it sells here: your product or service.
Record its intended customer here: your target customer.
Record exactly three brand-voice words here: your three voice words.

Make the Profile Testable

Concrete voice words give you a clear standard for judging the captions. A distinctive signature phrase gives you an exact string to search for.

Record the look you want for promotional images here: your visual style.
Record exactly two brand colors here: your two brand colors.
Record one distinctive signature phrase here: your distinctive signature phrase.
Record one real weekly promotion here: your first promotion.

Your profile now captures the brand details that repeated social posts need. Keep every profile detail out of the baseline prompt so the comparison stays fair.

Test the one-off prompt

A baseline captures the result before reusable instructions are introduced. This one supplies the promotion while withholding every brand detail you recorded.

Start a new ordinary chat in Gemini Apps.

Before you submit the prompt, do you expect Gemini to reproduce a distinctive phrase it has never received?

Submit your first promotion by using this one-off prompt:

Create three social captions for this promotion: [[FIRST_PROMOTION="your first promotion"]].

What Does This Prompt Test?

The prompt gives Gemini only the details of your first promotion.
The prompt leaves out your business profile plus your signature phrase.

Review the three captions for wording that could fit many businesses.
Press Cmd+F on macOS or Ctrl+F on Windows to open the browser page search.
Enter your distinctive signature phrase in the search field.

You should find no occurrence of the exact signature phrase in the response. The captions rely only on the short promotion you submitted.

What Does the Missing Phrase Prove?

The absence is the intended result. An ordinary new chat has no access to the business profile that stayed outside the prompt.

You now have a control result for judging whether the reusable workflow carries brand context into future chats.

Did the Baseline Test Behave Differently?

Confirm the submitted prompt contains only your first promotion.
Remove any business profile details from the ordinary chat.
Replace the signature phrase with a more distinctive phrase if Gemini produced it by coincidence.
Repeat the prompt in another new ordinary chat.

Help me check my one-off Gemini prompt comparison.

You have exposed the weakness of rebuilding social content from a one-off prompt. Next, you will save the missing brand context inside a reusable Skill.

Create Your Social Skill

The ordinary Gemini Apps chat produced generic captions because it could only use the promotion you submitted. Your recorded business profile stayed outside that chat.

A Skill stores reusable instructions for future chats. You will save your brand context plus output rules inside one Skill.

In this step, get ready to:

Create a saved Skill named create-weekly-social-post.
Store your business profile plus the required output rules.
Generate three branded captions plus Image 1 from one promotion message.

Create the Skill shell

The Skill name identifies the reusable workflow. Its description tells Gemini when that workflow applies.

Return to Gemini Apps from earlier.
Click Customize in the sidebar.

You should see the customization area that contains your available Skills.

Select Skills.
Click Create.

You should see the available Skill creation options.

Select Create manually.
Enter create-weekly-social-post in the name field.
Add the Skill description by copying this text into the description field:

Creates three on-brand social captions, hashtags, and one matching promotional image for a small business. Use when the user provides a weekly promotion in one or two sentences.

Why This Description Works

The first sentence defines the Skill's output. The second sentence defines the request that should activate it.

Confirm the name field shows create-weekly-social-post.
Confirm the description ends with one or two sentences.

Add the reusable instructions

The instructions become the Skill's saved memory. They combine your business profile with guardrails for captions plus image generation.

Add your recorded business profile to the Instructions field by using this template:

BUSINESS PROFILE
Business name: [[BUSINESS_NAME="your business name"]]
What it sells: [[PRODUCT_OR_SERVICE="your product or service"]]
Target customer: [[TARGET_CUSTOMER="your target customer"]]
Brand voice: [[THREE_VOICE_WORDS="your three voice words"]]
Visual style: [[VISUAL_STYLE="your visual style"]]
Brand colors: [[TWO_BRAND_COLORS="your two brand colors"]]
Signature phrase: [[SIGNATURE_PHRASE="your signature phrase"]]

What Does the Business Profile Save?

This section gives every future request the same audience plus brand identity. The signature phrase creates an observable test that proves the Skill reused its saved context.

Confirm the business profile contains your recorded values.
Confirm the section ends with your distinctive signature phrase.

Add the default workflow directly below the business profile by copying this text:

DEFAULT WORKFLOW
When the user provides a promotion:
1. Use the business profile above without asking the user to repeat it.
2. Do not invent prices, dates, discounts, locations, availability, or product details. If a detail is not supplied, leave it out.
3. Write exactly three distinct social captions. Give each caption a different opening hook, keep all three aligned with the brand voice, include a clear call to action, and add a short group of relevant hashtags.
4. Use the signature phrase naturally in exactly one caption.
5. Attempt to generate one original promotional image with Nano Banana that matches the offer, target customer, visual style, and brand colors. Keep prices, dates, hashtags, logos, and other written copy out of the image.
6. Whether or not the image appears, finish with a section called Fallback image prompt. Write one standalone, ready-to-paste image prompt that would create the same visual in Gemini's Create images tool.

What Does the Default Workflow Control?

The fact rule prevents Gemini from adding unsupported promotion details.
The caption rules require three different hooks plus one signature-phrase use.
The image rule gives Nano Banana 2 the saved visual direction.
The fallback rule preserves an image-generation path when a direct image does not appear.

Confirm the default workflow contains six numbered rules.
Confirm the sixth rule requires a standalone fallback image prompt.

Add the required response structure directly below the default workflow by copying this template:

OUTPUT FORMAT
Caption 1
Caption and hashtags

Caption 2
Caption and hashtags

Caption 3
Caption and hashtags

Image
Generate one matching image

Fallback image prompt
Standalone image-generation prompt

Why Use an Output Template?

The template gives every promotion the same predictable structure. The fixed headings make the captions plus fallback prompt easy to find.

Confirm the output format lists three caption headings.
Confirm the final heading says Fallback image prompt.

Add the captions-only rule at the bottom of the instructions by copying this text:

CAPTIONS-ONLY MODE
If the user's message includes the words captions only, create the requested captions but do not generate an image or include a fallback image prompt.

What Does Captions-Only Mode Do?

This conditional mode suppresses image generation for requests containing captions only. It gives the same Skill a text-only path for later quality checks.

Confirm CAPTIONS-ONLY MODE is the final section.
Click Create to save the Skill.

That setup is complete. You should now see an active Skill named create-weekly-social-post.

Is the Skill Missing or Unsaved?

Check that the name uses lowercase words separated by hyphens. Confirm the description plus instructions fields contain text.

Return to the Skills page to confirm create-weekly-social-post appears in your saved Skills.

Help me check why my Gemini Skill was not saved.

Test the Skill in a fresh chat

A fresh chat tests whether the Skill carries your brand rules forward. The promotion message stays short because the saved instructions supply the missing context.

Start a new Gemini chat.
Enter / or @ if that shortcut is shown.
Select create-weekly-social-post.

Before you submit the promotion, which saved brand details do you expect Gemini to reuse?

Submit only your first promotion by using this message:

[[FIRST_PROMOTION="your first promotion"]]

Why Is the Message So Short?

The message contains only the current promotion. The selected Skill supplies the business profile plus output rules from its saved instructions.

You should see three caption sections plus an image area. You should also see a standalone fallback image prompt at the end.

Count exactly three distinct captions.
Confirm each caption includes a clear call to action.
Confirm each caption includes relevant hashtags.
Find your exact signature phrase in one caption.
Confirm the signature phrase appears exactly once.
Locate the Fallback image prompt section.

Use the branch that matches your result. This keeps the project at exactly one generated image so far.

✔️ The Skill generated an image

The direct image completes the first promotion package.

Keep the generated image as Image 1.

ⓧ No image appeared

The fallback prompt carries the same visual direction into Gemini's dedicated image tool.

Copy the text beneath Fallback image prompt.
Open the tools menu in Gemini.
Select Create images.
Select Nano Banana 2 as the image model.
Paste the copied fallback prompt.
Submit the image prompt.
Keep the generated image as Image 1.

You should see one original promotional image based on the fallback prompt.

Confirm Image 1 matches the first promotion.
Confirm Image 1 reflects the target customer.
Confirm Image 1 follows the saved visual style.
Confirm Image 1 uses the two brand colors.
Confirm Image 1 contains no written copy.
Confirm Image 1 contains no logo.

That is the first reusable win. Your short promotion now produces the full branded package.

Your reusable Skill now produces captions plus an image from one short request. Next, you will audit the result and strengthen one saved instruction.

Refine the Brand Fit

Your reusable Skill has already produced three branded captions plus Image 1 from one short promotion. That result proves the saved workflow can carry your brand context into an output.

A repeatable workflow still needs a quality check before it can represent the business consistently. In this step, you will audit the first result before saving one precise refinement.

In this step, get ready to:

Audit the first promotion against five brand-fit checks.
Save one precise instruction that strengthens the weakest caption check.
Rerun the first promotion without generating another image.

Audit the first result

An evaluation works best when each requirement has a visible test. These five checks turn brand fit into evidence you can compare.

Switch back to the first promotion Skill chat from the previous step.
Compare the supplied promotion facts with all three captions.
Compare each caption's tone with all three voice words.
Check that each caption begins with a distinct hook.
Confirm that exactly one caption uses the signature phrase.
Compare Image 1 with the saved visual style.
Compare the colors in Image 1 with the two saved brand colors.
Identify the caption check with the most room to improve.

Your audit now gives you one specific improvement target. Even a strong first result benefits from a deliberate refinement.

Add one precise refinement

A precise instruction describes one behavior that the Skill can reproduce. Narrowing the rule to the weakest caption check gives the rerun a clear pass condition.

What Makes a Refinement Precise?

For promotion facts, specify which supplied detail must remain unchanged.
For voice, turn the weakest voice word into an observable writing rule.
For hooks, name the repeated opening pattern the Skill should avoid.
For the signature phrase, describe how it should fit naturally into one caption.

Return to Gemini Apps.
Select Customize in the sidebar.
Select Skills.
Select create-weekly-social-post.
Find the instruction tied to the weakest caption check.
Add one precise refinement sentence directly beside that instruction.
Select Save.

The active Skill now includes your refinement. That gives the next rerun one precise change to test.

Test the refinement without another image

A controlled rerun keeps the promotion unchanged. Any visible improvement can therefore be traced back to the saved instruction.

Return to a Gemini chat from earlier.
Type / or @ in the message box if the shortcut is shown.
Select create-weekly-social-post.
Enter the first promotion from earlier.
Add captions only to the end of the message.

Before you submit, which part of the captions do you expect your saved instruction to change?

Submit the message.

The response contains revised branded captions. It contains no image or Fallback image prompt section.

Compare the revised captions with the first set.
Confirm that the refined requirement is visible in the revised captions.
Confirm that the response contains no image.
Confirm that the response omits the Fallback image prompt section.

Your saved rule now changes the captions on demand. Image 1 remains the only image created so far.

Does the Rerun Look Wrong?

Return to the Skill editor to confirm the refinement sentence is still present.
Select Save if the refinement was not saved.
Check that the test message ends with captions only if an image or fallback prompt appears.

Help me diagnose the refinement test.

Your Skill now carries a tested refinement instead of unreviewed first-draft instructions. Next, you will prove that the saved brand context survives a different promotion in a fresh chat.

Test a Fresh Promotion

The saved Skill now produces improved captions for the first promotion. This final test checks whether that saved context survives a completely fresh chat.

Weekly offers change. You will send a different promotion through Gemini Apps without repeating the business profile or output rules.

In this step, get ready to:

Define a different second promotion for the same business.
Invoke the saved Skill in a completely fresh chat.
Verify the branded captions plus the second promotional image.

Plan a distinct test case

A useful reuse test changes the promotion while keeping the business fixed. That contrast shows whether the Skill carries the brand rules on its own.

Keep the same business from your saved profile.
Base the promotion on a different offer for that business.
Limit the promotion to one or two sentences.
Include only facts that the captions may repeat.

Run the Skill in a fresh chat

A fresh chat removes the earlier conversation as a source of context. The Skill must supply every saved brand detail.

Start a completely fresh chat in Gemini Apps.
Type / or @ if that shortcut is shown.
Select create-weekly-social-post.
Enter only the second promotion you recorded above.

Before you submit it, do you think a blank conversation can recover the saved voice plus the signature phrase?

Submit the second promotion.

You will see three distinct captions shaped by the saved brand voice. Exactly one caption uses the signature phrase.

The Skill also attempts one matching promotional image. It finishes with a standalone Fallback image prompt.

Choose the path that matches your fresh-chat result.

✔️ The image appears in the Skill response

The direct image completes the one-message workflow. Keep this single result as the second image in your project.

Keep the generated image as Image 2.
Confirm the image matches the second promotion.
Confirm the image follows the saved visual style plus the two brand colors.
Confirm the image contains no written promotional copy.
Stop image generation after this single result.

You now have one image for each promotion.

ⓧ The image does not appear

The fallback prompt carries the same visual requirements into the dedicated image tool. This path still creates exactly one second image.

Find the Fallback image prompt section in the Skill response.
Copy the standalone image prompt.
Select Create images from the tools menu.
Paste the copied fallback prompt.
Submit the prompt to generate one image.
Keep the generated result as Image 2.
Stop image generation after this single result.

You now have one image for each promotion.

Still Missing Image 2?

Select Create images from the tools menu before submitting the fallback prompt.
Submit only the standalone fallback prompt from the Skill response.

Ask for help if the fallback path still does not generate an image: Help me troubleshoot image generation in Gemini Apps without creating more than one Image 2.

Verify the saved brand context

A reusable workflow changes the subject while preserving the constraints. Your final audit checks both sides of that test.

Before you audit the result, which saved brand details do you expect to find?

Count the captions in the fresh-chat response.
Identify the opening hook in each caption.
Confirm that the three opening hooks are distinct.
Compare the caption tone with the three saved voice words.
Count the exact signature phrase across the three captions.

What Makes This Reusable?

The second promotion changes the subject. The Skill preserves the brand rules without another setup prompt.

Inspect Image 2 for the second promotion's subject.
Compare Image 2 with the saved visual style plus the two brand colors.
Confirm that Image 2 contains no prices or dates.
Confirm that Image 2 contains no hashtags or logos.
Find the standalone Fallback image prompt in the fresh-chat response.
Count the project images to confirm that only Image 1 plus Image 2 exist.

You will find three captions with different opening hooks. Their tone matches the three saved voice words.

The signature phrase appears naturally in exactly one caption. The response still contains the fallback image prompt.

The second image matches the new promotion plus the saved visual direction. Your project now contains exactly two promotional images.

You have proved the workflow is reusable. A new promotion now needs one short message instead of another full brand setup.

Secret mission

Add Campaign Sequence Mode

Turn one promotion into three connected campaign posts with distinct purposes. Extend your saved Skill without changing its default workflow or creating a third image.

Clean Up Your Resources

Choose whether to keep your saved Skill active, deactivate it for now, or delete it from Gemini Apps. This project costs $0 with a personal Google Account, subject to Gemini Apps usage limits.

Resources you used:

One saved active Skill named create-weekly-social-post containing your business profile, reusable social workflow, refinement instruction, captions-only mode, and campaign sequence mode.

Keep everything running

No action needed. Choose this if you want Gemini to keep using your saved workflow for future promotions.

Leave create-weekly-social-post active so Gemini can use it when relevant or when you select it in a chat.
Keep your existing Gemini chats as evidence of the baseline, refinement, fresh-chat test, and campaign sequence test.
Retain Image 1 and Image 2 as the finished promotional visuals from your workflow.

Pause - I'll come back to this later

Deactivate the Skill to stop automatic use while preserving its saved instructions. You can return to the Skill when you are ready to create another promotion.

Return to Gemini Apps in your browser.
Click Customize in the sidebar.
Select Skills.
Open create-weekly-social-post.
Click More.
Select Deactivate.

The Skill remains saved with your business profile and campaign sequence mode. Gemini stops using it automatically until you reactivate it.

Delete - I don't want to use this again

Deleting the Skill is permanent. Saving its instructions first protects your work if you change your mind later.

Return to Gemini Apps in your browser.
Click Customize in the sidebar.
Select Skills.
Open create-weekly-social-post.
Copy the Skill instructions into a document you control if you may want to reuse them.

Your copied instructions preserve the business profile and reusable workflows outside Gemini Apps.

Return to the Skills page.
Hover over create-weekly-social-post.
Click More.
Select Delete.

You no longer see create-weekly-social-post on the Skills page. This confirms that the saved Skill has been removed.

Nice Work!

You did it! You turned a repeated weekly posting task into a reusable workflow in Gemini Apps. Your saved Skill now transforms a short promotion into branded captions plus a matching promotional image.

You've learned how to:

Build a reusable brand workflow that carries saved business context into completely fresh chats.
Generate two complete promotion packages. Each package contains three branded captions plus one matching image.
Run a brand-fit audit against five checks. Save one precise refinement that visibly improves the next captions.
Secret Mission: Add a captions-only campaign sequence mode. It produces coordinated posts labeled Announce, Remind, and Last chance without creating a third image.

Ready to quiz yourself?