Experience with agent frameworks such as LangGraph, Microsoft Agent Framework, OpenAI Agents SDK, Claude Agent SDK, or Google ADK, and eval and observability tools such as Langfuse, LangSmith, Braintrust, or Arize Phoenix. Techniques that define best practice today, such as context engineering, MCP-based tool integration, skills, sub-agent orchestration, and LLM-as-judge evaluation, barely existed a few years ago and will look different a year from now.