> ## Documentation Index
> Fetch the complete documentation index at: https://docs.telli.com/llms.txt
> Use this file to discover all available pages before exploring further.

# What cannot be prompted

Although the system prompt is the core of the agent and plays a crucial role in shaping its behavior, it cannot control every aspect of the system. Below are a few examples of areas that cannot be influenced solely through the prompt.

### Examples

| **Item**                         | Description                                                                                                               |
| :------------------------------- | :------------------------------------------------------------------------------------------------------------------------ |
| **Voice (speed, volume, pitch)** | Determined by the TTS provider (Cartesia/ElevenLabs), not by the prompt                                                   |
| **Timing / Pauses**              | The agent has no sense of time; "wait 2 seconds" is ignored                                                               |
| **First Message**                | Set in the "First Message" field in the agent settings, not in the system prompt                                          |
| **Silence Handling**             | The idle handler is system behavior; the prompt can only trigger `waitForUserToReturn` as a tool call                     |
| **Call Outcomes**                | Extracted from the transcript after the call, not set by the agent during the call                                        |
| **Tool Calls**                   | The prompt defines when a tool is called; the system automatically provides the current parameter definition to the agent |

<small>*This table shows examples. The list is not exhaustive and can be extended based on your use case.*</small>