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

# Node Overview

> The five categories of nodes: Agent, Component, Conversation, Tools, and Post-Processing.

# Node Overview

Every element on the Voiceblox canvas is a **node**. Nodes are grouped into five categories.

## Agent

The **Agent** node is the central orchestrator. There is exactly one per flow.

| Node    | Description                                                                                                  |
| ------- | ------------------------------------------------------------------------------------------------------------ |
| `Agent` | Configures the agent's name, persona (system prompt), and language; connects to all component and tool nodes |

## Component

Component nodes define the AI capabilities of your agent.

| Node     | Handle      | Description                             |
| -------- | ----------- | --------------------------------------- |
| `LLM`    | `llm_in`    | Language model for generating responses |
| `TTS`    | `tts_in`    | Text-to-speech for voice output         |
| `STT`    | `stt_in`    | Speech-to-text for voice input          |
| `Avatar` | `avatar_in` | Visual avatar rendering (optional)      |

## Conversation

Conversation nodes form the **step chain** — the sequence of actions during a call.

| Node         | Description                                        |
| ------------ | -------------------------------------------------- |
| `Start`      | Entry point. Agent speaks its opening line.        |
| `Burst`      | A fixed number of back-and-forth exchanges.        |
| `Open Talk`  | Unlimited free-form conversation on a topic.       |
| `Timer`      | Conversation capped at a time duration.            |
| `If/Else`    | Binary branch based on an LLM-evaluated condition. |
| `Categorize` | Multi-way branch by semantic classification.       |
| `Transfer`   | Hand off to another agent or phone number.         |
| `End`        | Terminates the conversation.                       |

## Tools

Tool nodes connect to the Agent's `tools_in` handle and give the LLM access to external capabilities during a conversation.

| Node           | Description                                          |
| -------------- | ---------------------------------------------------- |
| `MCP`          | Exposes tools from an MCP server to the LLM          |
| `Exa`          | Gives the LLM real-time web search via Exa.ai        |
| `SIP Transfer` | Lets the LLM transfer a call to a human phone number |

## Post-Processing

Post-processing nodes run after the conversation ends. Chain them after an **End** node.

| Node                | Description                                                       |
| ------------------- | ----------------------------------------------------------------- |
| `Structured Output` | Extracts structured data from the conversation using an LLM       |
| `Webhook`           | Fires an HTTP POST with conversation data to an external endpoint |

## Connection diagram

```
[LLM] ──llm──▶ [Agent] ◀──tools── [MCP / Exa / SIP Transfer]
[TTS] ──tts──▶    │
[STT] ──stt──▶    ▼
              [Start] ──▶ [Burst] ──▶ [End]
                                        │
                             [Structured Output] ──▶ [Webhook]
```