langchain-agents

| Chat Models | LLM interface | Unified API across providers | | Agents | Tool use + reasoning | ReAct pattern | | Chains | Sequential operations | Composable pipelines | | Memory | Conversation state | Buffer, summary, vector | | Retrievers | Document lookup | Vector search, hybrid | | Tools | External capabilities | Functions agents can call |

| ReAct | Reason-Act-Observe loop | General tool use | | Plan-and-Execute | Plan first, then execute | Complex multi-step | | Self-Ask | Generate sub-questions | Research tasks | | Structured Chat | JSON tool calling | API integration |

| Name | How agent refers to tool | | Description | When to use (critical for selection) | | Parameters | Input schema | | Return type | What agent receives back |