clarify utility functions

docs/guide.md

@@ -30,18 +30,16 @@ These system designs should be a collaboration between humans and AI assistants:
 
 1. **Project Requirements**: Clearify the requirements for your project.
 
-2. **Utility Functions**: The AI system acts as the decision-maker, but it relies on **external utility functions** for input/output and tool usage.
+2. **Utility Functions**: Although the AI system is the decision-maker, it relies on **external utility functions**:
 
-   - **Example Utility Functions**:
-      - Reading inputs (e.g., getting Slack messages, reading emails)
+   <div align="center"><img src="https://github.com/the-pocket/PocketFlow/raw/main/assets/utility.png?raw=true" width="400"/></div>
+
+   - Reading inputs (e.g., retrieving Slack messages, reading emails)
    - Writing outputs (e.g., generating reports, sending emails)
    - External tool usage (e.g., calling LLMs, searching the web)
-
-   - **Example Non-Utility Functions**:
-      - LLM-based tasks (e.g., summarizing text, analyzing sentiment). These tasks are **core internal functions** built on top of the utility functions and will be designed in step 3.
+   - **LLM-based tasks** (e.g., summarizing text, analyzing sentiment) are **not** utility functions. Instead, they are *internal core functions* within the AI system—designed in step 3—and are built on top of the utility functions.
 
    -  > **Start small!** Only include the most important ones to begin with!
-      > <div align="center"><img src="https://github.com/the-pocket/PocketFlow/raw/main/assets/utility.png?raw=true" width="400"/></div>
       {: .best-practice }
 
 3. **Flow Design (Compute)**: Create a high-level design for the application’s flow.