In modern agentic frameworks like LangGraph or LangChain, the standard workflow for creating an autonomous tool-calling agent follows a specific sequence. First, tools must be defined (often as Python functions with clear docstrings, which the LLM uses to understand the tool's purpose). Second, the agent logic is defined, which specifies how the LLM should think. Third, the agent is initialized using a logic pattern like ReAct (Reason + Act). The ReAct framework is essential here because it enables the 'orchestrator' loop: the LLM receives a prompt, generates a 'Thought' about which tool to use, generates an 'Action' to call that tool, receives an 'Observation' (the tool's output), and repeats until it can provide a final answer. Loading tools into 'separate agents' (C) or defining tools 'inside' agents (D) are non-standard patterns that add unnecessary complexity and do not align with the centralized orchestration model required for LangGraph.