Build an AI Agent from Scratch: 50 Lines of Python to Understand Core Concepts

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🩺 Summary

Build a thinking, tool-using AI agent in pure Python + OpenAI API - zero frameworks, 50 lines, complete understanding.

📝 Details

## The Agent Core Loop 1. Receive user input 2. LLM decides: answer directly or use a tool? 3. If tool needed -> call tool -> feed result to LLM -> back to step 2 4. If direct answer -> output to user ```python def run_agent(user_input): messages = [{'role': 'user', 'content': user_input}] for _ in range(5): response = client.chat.completions.create( model='gpt-4o-mini', messages=messages, tools=tools) msg = response.choices[0].message if msg.tool_calls: # execute tool pass else: return msg.content ``` Agent = LLM + Tools + Loop. Master these 50 lines and any framework becomes just configuration.