How to build a ChatGPT plugin for your company’s voice & tone (formerly custom GPTs)

Somewhere in the last few months, someone has probably asked you, “So… can AI just write all our internal emails now?”

And you, being a responsible internal communicator, felt your soul briefly leave your body.

Because yes, AI can help.

But it doesn’t automatically understand your tone, your timing, your culture, why your CEO is allergic to exclamation points, or that YOU ARE A DIE-HARD FAN OF THE OXFORD COMMA.

That’s exactly where ChatGPT plugins (formerly custom GPTs) come in. Not as replacements for your judgment, but as writing partners who already understand your voice: the voice you’ve worked hard to protect.

Quick update, fall 2026: OpenAI is retiring custom GPTs and replacing them with plugins. Good news, almost everything in this guide still applies! Your old instructions box is now a “skill,” your uploaded examples are now “reference files,” and if you already built a GPT, there’s a button to move it over. We’ll walk through that below.

Let’s walk through what a plugin actually is, why it’s not scary, how to build one that sounds like your company, when it makes sense to create more than one, how to move a GPT you already have, AND how to keep it trained over time without making it your new part-time job.

So… what actually is a ChatGPT plugin?

A plugin is just ChatGPT with better instructions and better examples (your instructions and your examples), packaged up so you can reuse them. No coding. No special tools. No “deploying” anything.

You tell it how your company communicates, you show it real internal messages you’ve written, and it learns your tone the way a new teammate would.

That’s it!

(Plugins can do more, like connect to other apps and tools, but you don’t need any of that for a voice and tone plugin.)

What does “training” really mean?

Nothing complicated. You:

• Write down the rules (tone, structure, boundaries). This becomes your plugin’s skill.
• Add examples (your writing, leadership writing, your favorite Workshop email templates). These become your reference files.

Then the model absorbs your patterns and starts rewriting content in your voice instead of its own default style. (Keep scrollin’ for the full walkthrough!)

Gather the pieces that already feel like you

Before you open the builder, collect a handful of things you’re proud of:

• a few internal emails that feel unmistakably on-voice
• an all-hands recap with a nice flow
• a leadership update you managed to humanize
• marketing copy that you really loved
• your unofficial “tone playbook” (how you talk, how you don’t, your habits, your no-go words)
• your official brand guide

This is what your plugin will learn from. Not theoretical statements, but your actual communication patterns.

Give your plugin a job small enough to be successful

The biggest mistake people make? They tell their plugin to “help with internal communications” or “act like an internal communicator.” Bless its heart, it will try. But the job is too big, and that’s when the weird stuff happens.

For this plugin (the one meant to match your voice), give it one clear job: Rewrite content into our company voice. Scope it more to an assignment or a particular task than an entire role.

So this one isn’t for brainstorming or outlining. It’s just rewriting. And honestly, this is where voice and tone plugins shine. They can:

• smooth leadership drafts
• reshape long updates into readable messages
• adjust tone for each audience
• clean up structure
• make your rough drafts look polished without rewriting the meaning

If you need brainstorming or outlining, you can ALWAYS create separate plugins for those tasks.

Why multiple plugins = fewer headaches

Internal comms isn’t just one type of writing. It’s like ten:

• email
• Slack
• SMS
• intranet posts
• scripts
• onboarding sequences
• leadership announcements
• frontline updates
• crisis messages
• policy explainers

One plugin trying to juggle all of those tones and contexts can be TOUGH. Instead, try building them to be small and specialized. It’s a pretty common workflow for me to generate the initial draft in a “channel”-oriented plugin, and then pull it into the company voice & tone plugin to clean it up. I find that it’s really hard to get one plugin to cover allllll the nuances that go into creating a piece of comms, and a ton of conflicting instructions just means it’ll drift off.

A few I’ve built, and loved, outside of our Voice & Tone bot (they all started life as custom GPTs!):

• RickGPT (rewrites content into our CEO’s voice, trained on his presentations, emails, and LinkedIn posts)
• JamieGPT (same thing, but for myself)
• Should We Brand This? (factors in all of my branding preferences, effort vs. impact, etc. to properly scope a project and determine if it needs a logo, name, swag, etc.)
• HMC Sourcerer (pulls the latest interesting internal comms articles, research, videos, etc. for our Happy Monday Club newsletter)

There are SO many awesome use cases for plugins (and plenty in ChatGPT’s plugin directory, too, to mess around with!)

Write your instructions like you’re onboarding a new teammate

Okay, so you’re ready to build your own plugin for your brand’s voice and tone. Let’s do it!

Inside your plugin’s skill instructions, describe:

• your tone (warm, steady, people-oriented)
• your pacing (shorter paragraphs, clean transitions)
• your emotional range
• what to avoid
• how humor behaves
• how employees should feel when they read your messages
• accuracy rules (no invented data, no imaginary quotes)
• what to do when information is missing
• how your leaders prefer to sound
• if it should avoid classic AI tells (things in threes, the em dash, “it’s not this, it’s this” language, you know the drill!)

Then, add your examples as reference files! I do a mix of loading content there + actually sharing little snippets and examples directly in the chat. There are lots of resources on better ways to do this; mine is pretty scrappy. I’ve seen a lot about writing instructions in markdown and adding files/knowledge just as text, but this has gotten me results I’m fairly happy with.

A quick note on models: This is where you should experiment. Models change fast (the ones I compared when I first wrote this are already old news!), and some are a lot wordier than others. Try a couple on the same rewrite and keep whichever one sounds most like you.

Test it on something friendly first

If it’s sensitive or super high-stakes, that might not be your best initial use case. Keep it approachable and then tweak from there!

You can try a:

• newsletter intro
• weekly update
• Slack-sized version of a longer message

You’ll know quickly if it “gets” you. If not, tweak the rules or add a better example and try again. It may take a bit of refining, but usually not hours and hours.

Once it clicks, it becomes one of those “oh wow, I get hours back every week” moments!

Already built a custom GPT? Here’s how to move it

If you built a custom GPT before the switch, you don’t have to start over. In ChatGPT, open My GPTs and look for Migrate to plugin. Your instructions turn into a skill, your knowledge files carry over as reference files, and connected apps can come along too.

A few things to know before you click:

• Mind the deadline. OpenAI plans to retire custom GPTs on December 11, 2026 (timing can vary, and some Enterprise workspaces have until February 11, 2027). GPTs that aren’t migrated won’t be accessible after that.
• Some things stay behind. Your chosen model, your sharing settings, and your old conversations don’t move over.
• It starts out private. Once you’re happy with it, re-share it with your team.
• Give it a vibe check. Migrated plugins can behave a little differently, so run one on a rewrite you know well and tighten the instructions if it drifts.

How to train your plugin over time (the easy way)

Ongoing “training” is not a whole production, don’t worry! It’s pretty much the same kind of upkeep you already do with templates, talking points, and onboarding docs.

1. Add fresh writing samples occasionally

Anytime you think, wow, this message really sounds like us, add it to your reference files. Examples teach the model more than any rule you write!

2. Update the rules when your tone shifts

New leadership? Refreshed values? Employees suddenly allergic to long intros? Add a line or two to the skill instructions.

3. Remove outdated samples

If a piece no longer reflects your current tone, pull it. Old samples create an old voice!

4. Give it a quarterly “vibe check”

Rewrite something new and see if it stays on track. If it drifts (mine tend to do this, especially when it comes to that darn em dash), just tighten the instructions a bit.

5. Add examples for new types of work

More frontline messages? Shorter Slack updates? New onboarding flows? Go ahead and add a few samples so the model learns those patterns too.

6. Keep each plugin in its lane

If the rewrite plugin suddenly spends a month brainstorming content from scratch, it will drift. Let each one do exactly what it was built for.

Training is ongoing, but you can keep it light. Ten minutes here and there is plenty! (And you only need to spend time training the plugins you’re using often.)

How we think about AI at Workshop

Internal comms is usually one or two people holding up an entire company. So our take on AI is pretty simple: it should take the recurring work off your plate, so you have more time for the parts of the job you actually love. The strategy, the storytelling, and the relationships that make comms land.

That comes with a few non-negotiables for us:

• You’re the strategist. AI drafts, checks, and reports. You decide. Nothing goes out without a human saying “yes.”
• Your voice, not generic AI. This whole guide is about protecting how your company sounds. Your tools should do that by default.
• Grounded in your real data. The best help comes from your own content and results, working inside the permissions your team already has.
• Secure from the start. Workshop’s AI management system is independently certified to ISO/IEC 42001, so you’re not the one explaining AI risk to IT.

Meet Workshop AI Studio: your comms team just got bigger

A plugin like the one you just built is a great personal writing partner. If you want that kind of help built into your whole comms workflow, that’s exactly why we made Workshop AI Studio!

AI Studio gives you a team of agents that handle recurring work in the background (on a schedule, even!) and bring everything back to you for approval:

• Draft writer: hand over a prompt, a link, or last quarter’s update and get a real first draft back in seconds.
• Brand manager: every draft comes back looking and sounding like your company. Think of it as the voice and tone plugin from this guide, built right in.
• Copy editor: every send gets checked for tone, spelling, broken links, and accessibility before it goes out.
• Data analyst: ask what performed and get a straight answer on opens, best send times, and what made the most impact.
• Onboarding coordinator: new users get set up on Workshop automatically, and you hear about who still hasn’t logged in.

And here’s the fun part: you already know how to build your own. In AI Studio, if you can write instructions for a new teammate, you can build an agent. Same muscle you just practiced in this guide!

Already living in ChatGPT? Workshop’s MCP server connects your Workshop data to the AI tools your team already uses, including ChatGPT, Claude, Copilot, and Gemini. Check how a campaign performed or start a draft without switching windows.

Explore Workshop AI Studio!