Microsoft 365 Copilot extensions and plugins

Out of the box, Microsoft 365 Copilot grounds on the content already in your tenant — files, emails, chats, calendars. To extend Copilot to systems outside Microsoft 365 (ServiceNow, Salesforce, Jira, custom apps) you use Copilot extensions. There are several types and they're easy to confuse.

Extensions sit between the core product in What is Microsoft 365 Copilot and custom agents in Copilot Studio; the governance of what gets installed is in Copilot agents and Agent Store governance, Graph connectors are administered per Microsoft Search administration, and developers start from Teams app development for Copilot.

The extension types

1. Microsoft 365 Copilot agents (Copilot Studio)

Custom agents built in Copilot Studio, published to your tenant, accessible from inside Copilot Chat with @AgentName invocation. Each agent has:

• Knowledge sources — SharePoint sites, web URLs, Graph connectors.
• Actions — Power Automate flows, custom connectors, plugins.
• Personality and instructions that shape its behaviour.
• Permissions to specific users or groups in your tenant.

Best for: building a focused AI assistant for a specific business workflow — IT support agent, HR policies agent, sales product agent.

2. Graph connectors

Microsoft Graph connectors index external content into Microsoft Search and Copilot's grounding pool. A connector for ServiceNow, for example, indexes tickets so Copilot can reason about them alongside Microsoft 365 content.

Microsoft ships connectors for many systems; partners build many more; the Graph Connector SDK lets you write your own. Each connector has access controls and permission mapping so Copilot respects what the user can see in the source system.

Best for: making external knowledge bases part of Copilot's general grounding without requiring users to invoke a specific agent.

3. Message extensions

A message extension (Teams app construct) can return adaptive cards to the user in Copilot. Type a question, the extension returns a card with summarised data and quick actions. Used heavily for actionable surfaces like "show open tickets" or "create a record."

Existing Teams message extensions can be lit up as Copilot extensions with minimal change.

4. Plugins

Microsoft uses "plugin" inconsistently across product surfaces. In Copilot today, plugins typically refer to API-based extensions that let Copilot call third-party services on the user's behalf. The OpenAPI / Plugin model from the open Copilot platform is the foundation.

5. Copilot connector apps

Newer first-party connectors — line-of-business integrations from Microsoft and partners — let Copilot reason about and act on data in specific apps without you building anything custom.

How to choose

| Need | Extension type | | --- | --- | | Add a knowledge base to Copilot grounding | Graph connector | | Build a focused workflow agent | Copilot Studio agent | | Return actionable cards from a search | Message extension | | Let Copilot call an API | Plugin / API extension | | Off-the-shelf integration with SaaS X | First-party connector if it exists |

In practice many production scenarios combine multiple: a Graph connector for grounding, a Copilot Studio agent for orchestration, a Power Automate flow for actions.

Governance

Treat agents and connectors as published apps:

• Inventory them in the Microsoft 365 admin center.
• Apply app permission policies to control who can install or invoke them.
• Audit usage through Purview.
• Review the permissions each extension requests before approving.

Extending Copilot is where the platform becomes genuinely transformative for your specific business. The first agent takes a week; the tenth takes hours.