in n8n one of the node types is called the AI Agent, it contains 6 different “agents” in the drop down such as Tools Agent, Conversational Agent, etc, the node also contains the standard output and Chat Model, Memory and Tools outputs. Explain to me a description of all 6 agents purpose, use case, special consideration, requirements, unique value and real-world examples for each. Finally write a paragraph just emphasizing the differences and how to know when to use each.