LANGCHAIN-AGENTS
LangChain Agents agentic LLMs tool use ReAct.
Definition
LangChain Agents key concepts: (1) Agents: LLM-powered components that decide actions via Reasoning (chain-of-thought) + Acting (tool calls), iterate until completion or max iterations. (2) Tools: functions exposed to LLM (search engines DuckDuckGo + Google, calculator, custom Python functions wrapped as Tool, REST APIs, SQL databases, vector DBs, etc.), tool description Markdown LLM understands. (3) Agent types: ReAct Agent (most common, Reasoning + Acting iterative), Plan-and-Execute Agent (Planner + Executor LLMs separate), Conversational Agent (chat history aware), OpenAI Functions Agent (uses OpenAI function calling), Tool Calling Agent (modern, supports any LLM with tool calling capability). (4) AgentExecutor: runtime that orchestrates agent + tools, handles max_iterations, max_execution_time, error handling. (5) Memory: ConversationBufferMemory, ConversationSummaryMemory, etc. retain context across iterations. (6) LangGraph (since 2024): alternative to AgentExecutor, builds agentic workflows as graph (nodes = functions, edges = transitions), more control + visibility. Integration: LangSmith (observability + tracing + evals), LangServe (deploy LangChain apps via FastAPI), LangGraph Cloud (managed graph workflows). LangChain library Python + JavaScript, ~12000+ contributors 2024.
Origin
LangChain initial release October 2022 by Harrison Chase (ex-Robust Intelligence) ; LangChain Inc. founded 2023 ; Series A $25M April 2023 (Sequoia Capital + Benchmark) ; Series B negotiation 2024 ; ~80000+ GitHub stars 2024.
Example in context
Customer service AI assistant uses LangChain Tool Calling Agent: tools available = search company knowledge base, query CRM customer record, escalate to human ; user 'my order #12345 not arrived', agent reasons + calls CRM Tool (gets shipping info delayed) + calls Knowledge Base Tool (gets policy refund) + responds 'your order was shipped 5 days ago, expected today, here is tracking link + apologies if delayed'.
Related terms
- LangGraph — graph-based evolution.