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

# Using Assistants

> How to chat with your custom assistants

## Starting a Chat with an Assistant

1. Navigate to the **Assistants** section in the primary sidebar.
2. Select the assistant you want to use.
3. Click **New Chat** or start typing in the input field.

The assistant's system prompt is automatically applied to every message in the conversation, shaping how the AI responds.

## How the System Prompt Works

When you chat with an assistant, the system prompt you configured is sent as a hidden instruction to the AI model with every request. This means:

* The AI adopts the persona and rules you defined
* Responses follow the style and constraints you specified
* The behaviour is consistent across all conversations with that assistant

## Switching Models

Even within an assistant chat, you can switch the AI model using the model selector dropdown. The assistant's system prompt remains active regardless of which model you choose.

<Note>
  Switching to a different model may produce different response styles, even with the same system prompt. More capable models tend to follow complex instructions more accurately.
</Note>