The best Python AI agent frameworks in 2026

This roundup compares nine Python agent frameworks against criteria including model portability, durable execution, human approval, frontend and voice reach, MCP support, tracing and commercial support, and picks Pydantic AI overall for covering all of them in the open-source library. It then recommends LangGraph/LangChain, the OpenAI Agents SDK, Google ADK, Microsoft Agent Framework, Strands Agents, CrewAI, the Claude Agent SDK and Agno for specific vendor or design preferences, each with a stated catch. A comparison table lists model providers, durable execution engines, speech-to-speech voice, interfaces, MCP, observability, commercial support and license per framework, checked October 29, 2026.