Message roles

Message roles tell a model where each part of a conversation came from. Common roles include system, user, assistant, and tool.

Tiny example

system:    Answer from approved policy only.
user:      What is the refund period?
tool:      Policy 7 says 30 days.
assistant: The refund period is 30 days. [Policy 7]

Roles preserve structure, but they do not prove that content is trustworthy.

FDE note

Do not concatenate every value into one giant string when the model API supports structured messages. Keep tool outputs and user-provided content clearly separated, and validate both before use.