Declarative agents are intelligent assistants that rely on the base model and orchestration of Microsoft 365 Copilot. When you extend them with knowledge, they can reason over information that is not part of their model. By adding skills, you give agents the ability to interact with external systems, trigger certain behaviors based on system conditions, or use custom workflow logic.

One type of skill is actions, which allow a declarative agent to communicate with APIs, both to retrieve and modify data. You implement these actions using API plugins. API plugins enable declarative agents to call APIs. Plugins describe:

• The location of the API
• How an agent should authenticate when calling the API
• The functions, which represent the operations the API can perform
• The data structure the API expects in requests and returns in responses

API plugins consist of a definition that describes all this information and references an API specification containing details about the API. The API plugin definition and the API specification are included in the Copilot extension package. The API itself is hosted outside of Microsoft 365 and typically belongs to the external system it represents.

Declarative agents can use multiple API plugins connected to different APIs. This composability enables a flexible architecture that allows you to support various scenarios.

Next Unit: How Do API Plugins Work?