A production-based comparison of six major AI agent frameworks in 2026: Vercel AI SDK, LangGraph, Mastra, OpenAI Agents SDK, Pydantic AI, and Claude Agent SDK. The author, who has shipped production code on five of them, frames the decision around three key questions: language (TypeScript vs Python), need for provider portability, and complexity of control flow. Each framework is evaluated on what it does well, where it falls short, and when to pick it. The post also covers what no framework handles for you — observability, cost tracking, evals, and security — and closes with concrete recommendations for common use cases.
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What An Agent Framework Is Actually ForVercel AI SDKLangGraphMastraOpenAI Agents SDKPydantic AIClaude Agent SDKWhat About LlamaIndex, CrewAI, AutoGen, etc.How to Actually DecideWhat You Will Wish You Had Built In AnywayWhat I Would Actually Do Today2 Comments
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