Google Developers Blog published a step-by-step guide by Stephen Allen and Kaz Sato on building voice agents that stay conversational while slow tool calls run, using the open-source Agent Development Kit (ADK) and Gemini 3.8 Live. The guide says backend queries cannot always be sub-second, so the fix is architectural: streaming tools, non-blocking FunctionTool definitions, and response scheduling let the agent acknowledge a request immediately, narrate progress, and answer unrelated questions while a query continues in the background. The authors report that in their own sales-report benchmark on Gemini 3.8 Live, switching from a blocking tool to a streaming tool cut time to the agent's first words from 14.4 seconds to 1.2 seconds. The post also says non-blocking tools do not shorten the backend query itself. Requirements listed are google-adk 2.10.0 or later, Gemini 3.8 Live on Gemini Enterprise, and bidirectional live sessions (run_live) for streaming tools and live scheduling.