Overview
Major agent environments use files that can be inserted at the beginning of a conversation. The names vary by platform. Examples include Gemini instruction files, Agents instruction files, and Claude instruction files. The name is less important than the mechanism: the content is automatically prepended to the agent's working context.
This means the file behaves like a reusable prompt that is active in every relevant session. It can contain:
- User preferences.
- Style requirements.
- Naming conventions.
- Project rules.
- Technical decisions.
- Behaviors to avoid.
- Steps the agent must perform before or after a task.
- Instructions for updating memory or rules.
A simple demonstration is to place a personal naming preference and a sign-off instruction in the file. A new conversation then follows those instructions even though they were not typed in the current message. The file has become part of the agent's starting context.
The benefit is consistency. Repeated instructions no longer need to be copied into every request.