OpenAI Agents SDK overview

OpenAI Agents SDK (openai-agents-python) is OpenAI's framework for building agentic applications. It exposes a `Runner` that drives a streaming agent loop over the Responses API, supports handoffs/subagents, tools, and emits a structured streaming-event taxonomy (RawResponsesStreamEvent, RunItemStreamEvent + 11 item subtypes, AgentUpdatedStreamEvent). Features guardrails for input/ output validation, tracing for debugging and observability, and MCP tool server integration. The SDK emphasizes minimal abstraction over the Responses API while providing structured multi-agent patterns via handoffs.