Building custom AI agents requires understanding core architectures, implementing proper patterns, and following best practices. This guide takes you from basic concepts to production-ready implementations with step-by-step workflows.
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Start with a simple agent that can process inputs, maintain conversation context, and generate responses. Follow these steps to build your first agent:
Set up the base agent class with LLM client and configuration
Implement conversation history and context management
Handle user input and generate appropriate responses
Test your agent and deploy to production
# Basic Agent Implementation class SimpleAgent: def __init__(self, llm_client, system_prompt=None): self.llm = llm_client self.system_prompt = system_prompt or "You are a helpful AI assistant." self.conversation_history = [] self.max_history = 10 async def process(self, user_input): """Process user input and generate response""" # Add user input to history self.conversation_history.append({ "role": "user", "content": user_input }) # Prepare messages for LLM messages = [ {"role": "system", "content": self.system_prompt} ] + self.conversation_history[-self.max_history:] # Get LLM response response = await self.llm.chat.completions.create( model="gpt-4", messages=messages, temperature=0.7 ) # Extract and store response assistant_message = response.choices[0].message.content self.conversation_history.append({ "role": "assistant", "content": assistant_message }) return assistant_message # Usage Example agent = SimpleAgent(llm_client) response = await agent.process("What is machine learning?") print(response)
The ReAct pattern combines reasoning with action-taking, making agent behavior more transparent and controllable. Here's how to implement it:
Create structured prompts for reasoning steps
Extract actions and parameters from LLM responses
Run selected tools and gather observations
Continue reasoning until final answer is reached
# ReAct Agent Implementation class ReActAgent: def __init__(self, llm_client, tools): self.llm = llm_client self.tools = tools self.max_iterations = 5 async def execute(self, task): """Execute task using ReAct pattern""" prompt = f"""Task: {task} You will solve this step by step: Thought: [Your reasoning] Action: [Tool to use] Action Input: [Input for the tool] Observation: [Tool output - I'll provide this] Available tools: {', '.join(self.tools.keys())} When you have the answer: Thought: [Final reasoning] Final Answer: [Your answer] Begin: Thought: """ for iteration in range(self.max_iterations): # Get LLM response response = await self.llm.chat.completions.create( model="gpt-4", messages=[{"role": "user", "content": prompt}] ) content = response.choices[0].message.content # Check for final answer if "Final Answer:" in content: return self.extract_final_answer(content) # Extract and execute action if "Action:" in content: action = self.extract_action(content) action_input = self.extract_action_input(content) if action in self.tools: observation = await self.tools[action].run(action_input) prompt += content + f"\nObservation: {observation}\nThought: " return "Could not complete task within iteration limit" # Usage tools = {"search": SearchTool(), "calculate": CalculatorTool()} agent = ReActAgent(llm_client, tools) result = await agent.execute("Find the current weather in Tokyo")
Extend your agent's capabilities by integrating various tools and services. Follow this workflow to add tool support:
Create base tool class with standard methods
Build specific tools for different capabilities
Add tools to registry for agent access
Process tool calls with error handling
Tool Type | Use Case | Setup Time | Complexity |
---|---|---|---|
Web Search | Current information retrieval | 5 minutes | Low |
Database Query | Structured data access | 15 minutes | Medium |
API Integration | External service connection | 30 minutes | Medium |
File Processing | Document analysis | 20 minutes | High |
Get started quickly with our pre-built agent templates:
Deploy your agent to production with proper monitoring, scaling, and reliability features:
Implement comprehensive error recovery and logging
Track metrics, performance, and usage patterns
Set up auto-scaling and load balancing
Launch to production and monitor performance
# Production Agent Service with FastAPI from fastapi import FastAPI, HTTPException from pydantic import BaseModel import logging from datetime import datetime app = FastAPI(title="Production Agent API") class AgentRequest(BaseModel): message: str session_id: str = None context: dict = {} class AgentResponse(BaseModel): response: str session_id: str timestamp: datetime metrics: dict class ProductionAgent: def __init__(self): self.sessions = {} self.rate_limiter = RateLimiter(max_requests=100) self.metrics = { "total_requests": 0, "successful_requests": 0, "avg_response_time": 0 } async def process(self, request: AgentRequest) -> AgentResponse: """Process request with monitoring""" start_time = datetime.now() try: # Check rate limits if not await self.rate_limiter.check(request.session_id): raise HTTPException(status_code=429, detail="Rate limit exceeded") # Process message response = await self.generate_response(request.message) # Update metrics self.update_metrics(True, start_time) return AgentResponse( response=response, session_id=request.session_id, timestamp=datetime.now(), metrics={"processing_time": (datetime.now() - start_time).total_seconds()} ) except Exception as e: logging.error(f"Error: {str(e)}") self.update_metrics(False, start_time) raise agent = ProductionAgent() @app.post("/chat") async def chat(request: AgentRequest) -> AgentResponse: """Chat endpoint with production features""" return await agent.process(request) @app.get("/health") async def health(): """Health check endpoint""" return {"status": "healthy", "metrics": agent.metrics}
Coordinate multiple specialized agents working together on complex tasks with shared context and communication protocols.
Implement short-term and long-term memory systems with vector databases for persistent knowledge storage.
Train custom models on your specific data and use cases for improved performance and accuracy.
Handle real-time data streams and provide instant responses with WebSocket connections.
Build Retrieval-Augmented Generation systems for accurate, context-aware responses.
Test and validate agent performance with comprehensive evaluation metrics and benchmarks.