Every team has that one Slack or Teams channel where the exact same questions get asked every single week. Where is the updated brand guide? What is our policy on expense receipts over $50? How do we handle customer returns outside the 30-day window?
Instead of re-pasting links or typing out the same instructions for the hundredth time, you can build a custom AI assistant in about 10 minutes.
Trained exclusively on your team’s internal documentation, process manuals, and style guides, it acts as a digital know-it-all that answers questions accurately using your official guidelines as gospel.
Best of all? You don’t need to write a single line of code, and you aren’t locked into just one ecosystem. Whether your company uses AI from OpenAI, Anthropic, Google, or Microsoft, here’s how to set one up across all four major platforms.
Preparation and guardrails
Regardless of which AI tool you choose, every custom assistant relies on the same two core components: clean documentation and strict guardrails.
When it comes to preparation, the golden rule of building a custom assistant is simple: garbage in, garbage out.
- Consolidate files: Gather your official brand guides, standard operating procedures, or onboarding manuals into clean, standalone files (PDF, DOCX, TXT, or live Google Drive/SharePoint links).
- Remove outdated noise: Strip out redundant drafts, old dates, and expired policy notes before uploading.
- Format headers clearly: Use standard document heading styles. Clear structural hierarchy helps the language model map document sections accurately when retrieving answers.
Every platform gives you an Instructions or System Prompt box. Paste and adapt this exact instructions framework to keep your assistant from making up answers:
You are the official [Team Name] Knowledge Assistant. Your primary job is to answer questions using only the information provided in the uploaded Knowledge files.
1. Always prioritize exact facts, figures, and procedures found in the knowledge files over general web knowledge.
2. If a user asks a question that is not covered in the uploaded documentation, explicitly state: “I don’t have that information in our current documentation. Please check with your team lead.”
3. Do not make assumptions, invent policies, or pull unverified rules from outside sources.
4. Keep responses concise, direct, and formatted with bullet points for quick reading.
Choose your platform
Pick the platform that matches your team’s existing software subscriptions and workflow habits. Note that you’ll need a plus, pro, or enterprise subscription for most of these to work.
ChatGPT
- Open ChatGPT, click Explore GPTs in the sidebar, and click + Create.
- Click straight into the Configure tab (skip the interactive builder).
- Name your bot, paste your guardrail instructions into the Instructions box, and upload your prepped files under Knowledge.
- Test in the right-hand Preview pane, then click Create/Update and set permissions to Only people with a link or Anyone in your workspace.
Claude
- Open Claude and click Projects in the left sidebar.
- Click Create Project, name it, and set visibility permissions for your workspace.
- In the right-hand panel under Project Knowledge, upload your source files.
- Under Set Project Instructions, paste your guardrail prompt.
Gemini
- Open Gemini and click Gem Manager in the sidebar (or select New Gem).
- Name your Gem and paste your guardrail instructions into the Instructions box.
- Under Knowledge, attach your source files or link them directly from Google Drive.
- Save the Gem and share the link with your team.
Copilot
- Go to copilotstudio.microsoft.com (or open the Copilot app directly inside Teams) and select New agent.
- Under the Knowledge section, point the agent directly to your team’s SharePoint site, OneDrive folder, or uploaded documents.
- In the Instructions panel, paste your operational rules and guardrails.
- Test the agent and click Publish to deploy it directly as a pinned bot or channel app inside Microsoft Teams.
Note: Keep sensitive data out
While enterprise tiers of these tools keep your data private within your organization, practicing smart digital hygiene is essential.
It’s generally safe to upload brand guidelines, public-facing documentation, standard operating procedures, customer service templates, product catalogs, and general employee handbooks.
Don’t upload unencrypted customer databases, personal identifiable information, proprietary passwords or API keys, or unannounced financial records.
