adk-python

Agent Development Kit (ADK) is Google's open-source, code-first framework for building, evaluating and deploying AI agents. It applies ordinary software engineering practices to agents: you define agents, tools and orchestration in Python, test them, version them and deploy them like any other service. ADK is optimised for Gemini but is model-agnostic and deployment-agnostic, and it is also available for Java, Kotlin, Go and TypeScript.

Version 2.0 adds a graph-based workflow runtime for deterministic flows with routing, fan-out and fan-in, loops, retries, state and human-in-the-loop steps, plus a Task API for structured delegation between agents. You can compose specialised agents into hierarchies, give them pre-built tools, custom functions, OpenAPI specs or MCP tools, guard sensitive tools with explicit confirmation, and even define agents without code through Agent Config. A built-in web UI (`adk web`) helps you test, debug and evaluate agents, and deployment targets include Cloud Run and Vertex AI Agent Engine.

Getting started: requires Python 3.11+. Install with `pip install google-adk` (Google recommends its constraints files for dependency safety), create an agent, then run `adk web` to try it in the browser.