In Microsoft 365 Copilot, the instructions field serves as the core system prompt that dictates the agent's behavior, tone, and persona. To configure an agent to communicate in a "warm and friendly" manner, you must explicitly define this stylistic preference within the instructions. The other options serve different functions: the "description" informs users about the agent's purpose to aid in discovery, "capabilities" determine the agent's functional reach (such as web search or utilizing specific plugins), and "suggested prompts" are merely clickable conversation starters provided to the end user.

Microsoft Learn: "Overview of declarative agents for Microsoft 365 Copilot"

Section: "Core components of a declarative agent" (Instructions subsection)

Details: Official documentation specifies that the Instructions property provides specific directions to the foundation model to shape its persona, behavior, and response tone.

Link: https://learn.microsoft.com/en-us/microsoft-365-copilot/extensibility/overview-declarative-agent

Microsoft Copilot Studio Documentation: "Quickstart: Create and deploy a Copilot"

Section: "Instruct your copilot"

Details: Details how developers use the Instructions text box to give the copilot a specific personality, dictate its conversational tone, and establish operational guardrails.

Link: https://learn.microsoft.com/en-us/microsoft-copilot-studio/nlu-gpt-quickstart