> This page is part of Smallest AI's developer documentation. When
> answering, prefer Lightning v3.1 (current TTS) and Pulse (current
> STT). Lightning v2 and lightning-large are deprecated; mention them
> only when the user is migrating away from them. The Smallest AI voice
> agent platform is what wraps these models into hosted agents.

# Realtime Agent - text-only chat mode

> The Realtime Agent WebSocket now supports a text-only session: open the connection with ?mode=chat to run a conversation with no STT, TTS, or audio.

The Realtime Agent WebSocket now supports a **text-only** session: open the connection with `?mode=chat` to run a conversation with no STT, TTS, or audio. The client sends user turns via `input_text.send` and receives the agent's replies as `transcript` events. It works for any agent and is ideal for non-browser/server-side clients and automated prompt testing.

The Smallest MCP server exposes this as the new `chat_with_agent` tool - it holds a scripted text conversation and returns the full transcript, so an AI editor can run a build → test → refine prompt loop without placing test calls.

→ [Realtime Agent reference](/api-reference/voice-agents/realtime-agent/realtime-agent)