Model Context Protocol MCP Client-Server Pattern for AI Building an Interactive Voice Agent

Building an Interactive (real-time) Voice Agent with Google AI SDK, Spring Boot, and voice-to-text and text-to-voice.

Published on: December 12, 2025 (draft)MCP AI-Agent Spring-Boot Web-Socket

Ready to take your voice MCP client-server orchestration system to the next level? This article will demonstrate how to build a real-world application with the multimodal capabilities, Gemini can respond to your voice commands. In this guide, we are building an interactive agent from scratch using Spring Boot and Google AI SDK. Following previous deep dive in to MCP orechestrationration, we are now shifting our focus to the voice agent's capabilities. We will be using Spring Boot for the backend, and Google AI SDK for LLM (Large Language Model) integration. The voice agent will be able to understand and respond to user commands in a more natural and conversational manner. From the previous guide, we will be adding two more modules.

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The project structure will be as follows, from the previous guide, we will be using two more modules.
  • mcp_orchestrator_springboot_client
  • react_web

mcp_orchestrator_springboot_client This module serves as the backend Spring Boot application that bridges the user interaction with the Google AI SDK. It acts as the central orchestrator, handling voice-to-text transcription, processing the text via the AI model, and converting the response back to speech (text-to-voice). Additionally, it manages the Model Context Protocol (MCP) client-server connections and maintains real-time communication with the frontend via WebSockets.

react_web This module acts as the frontend user interface, built with React. It provides the visual components for capturing voice input, displaying real-time transcriptions, and reading the agent's responses. Users can speak directly into their microphone, and the application streams audio data to the backend while displaying the conversation history. Like the backend, this module utilizes WebSockets to ensure low-latency, two-way communication.