LangChain 4 Tool Calling, Function Calling, and MCP Systems: How LLMs Safely Interact with Software Dec 13, 2025 LangChain Cheat Sheet: Components, Patterns, and Production Rules Dec 12, 2025 LangGraph: Orchestrating LLM Agents via Explicit Control Graphs Jul 15, 2025 LangChain An Advanced Framework for Modular LLM Applications Jul 14, 2025