You want Copilot to follow strict rules when generating responses. Without clear boundaries, Copilot may produce output that is too broad, off-topic, or inconsistent with your organization’s policies. System instructions let you define exact guidelines for Copilot’s behavior across Microsoft 365 apps. This article explains what system instructions are, how to set them up, and how to avoid common mistakes.
Key Takeaways: Configuring System Instructions for Copilot
- Copilot Studio > Create > System instruction: Main location to write and save rule sets that constrain Copilot output.
- Microsoft 365 admin center > Copilot > System instructions: Central management page for tenant-wide instruction templates.
- Test in Copilot pane > Copilot Studio > Preview: Verify instructions produce expected behavior before publishing to users.
What Are System Instructions and Why Use Them
System instructions are a set of predefined rules that tell Copilot how to behave. They act as a permanent filter on every response. Without system instructions, Copilot relies only on its base model and the immediate context of your prompt. This can lead to responses that include unsupported opinions, irrelevant details, or prohibited content.
System instructions are stored in Copilot Studio and applied to a specific Copilot agent. You can create multiple agents with different instruction sets. For example, one agent for customer support and another for internal HR queries. The instructions override the base model’s default behavior for that agent only.
Prerequisites
Before you can use system instructions, you need the following:
- A Microsoft 365 subscription that includes Copilot for Microsoft 365 or Copilot Studio.
- Copilot Studio license assigned to your account.
- Global admin or Copilot admin role in the Microsoft 365 admin center.
- Access to copilotstudio.microsoft.com.
Steps to Create and Apply System Instructions
Follow these steps to create a Copilot agent with system instructions that constrain behavior.
- Open Copilot Studio
Go to copilotstudio.microsoft.com and sign in with your work account. Select the environment that contains your Copilot agents. - Create a new agent
Click Create in the left navigation. Choose New agent. Enter a name for your agent, for example “Support Bot Constrained”. Click Create. - Open the System instruction section
In the agent editor, locate the System instruction box. This is a plain text field where you type the rules. - Write your system instructions
Type clear, specific rules. Use short sentences. Start each rule on a new line. Example rules:You are a support assistant for Contoso Ltd.
Only answer questions about Contoso products and services.
Do not provide opinions or personal advice.
If a question is outside these topics, respond: I can only help with Contoso products. - Test the instructions
Click Preview in the top toolbar. The preview pane opens. Type a test question, such as “What is the weather today?” Verify Copilot returns the constrained response. - Publish the agent
Click Publish in the top toolbar. Confirm the publish dialog. The agent with your system instructions is now live for users. - Assign the agent to users
Go to Microsoft 365 admin center > Copilot > Agents. Select your agent and click Manage. Add users or groups who should use this agent.
Common Mistakes to Avoid
System Instructions Are Too Vague
If you write “Be helpful and professional,” Copilot still has too much freedom. It may generate long, irrelevant answers. Use concrete rules. For example: “Answer in three sentences maximum.” Test each rule in preview mode.
Instructions Conflict With Each Other
If you say “Always include a disclaimer” and then “Keep responses under 30 words,” Copilot may fail both rules. Review your instructions for logical conflicts. Remove any rule that contradicts another.
Not Testing After Publishing
Publishing does not validate your instructions. Always test in the Copilot pane after publishing. Open a Microsoft 365 app like Teams or Word. Open the Copilot pane and ask a question that violates your rules. If Copilot does not follow the rule, return to Copilot Studio and revise the instruction.
System Instructions vs Topics vs Plugins: Key Differences
| Item | System Instructions | Topics |
|---|---|---|
| Purpose | Global behavior rules for all conversations | Trigger specific flows for specific user intents |
| Scope | Applies to every response from the agent | Applies only when user matches a trigger phrase |
| Complexity | Plain text, no logic needed | Requires flow design with conditions and actions |
| Override priority | Low: Topics and plugins can override instructions | High: Activated topic overrides system instructions |
If Copilot Ignores Your System Instructions
Copilot may still violate your rules for three reasons. First, a triggered topic overrides system instructions. Check if a topic with a broad trigger phrase is capturing the query. Second, the instruction text contains ambiguous language. Rewrite rules using the word “must” instead of “should.” Third, your instruction is too long. Copilot has a limited context window for instructions. Keep the instruction text under 2000 characters.
To verify, open the agent in Copilot Studio and click Analytics. Review the Session transcripts to see exactly what Copilot received and responded. Compare the transcript with your system instruction to identify the gap.
You can now create Copilot agents with precise behavioral constraints using system instructions. Start by writing three to five concrete rules in Copilot Studio, then test each rule in preview mode. For more complex scenarios, combine system instructions with topics and plugins, but remember that topics can override your rules. Review session transcripts regularly to ensure Copilot stays within the boundaries you defined.