Building AI Agents: From Chatbots to Autonomous Systems



Building AI Agents: From Chatbots to Autonomous Systems

The AI landscape has shifted dramatically. We’ve moved beyond simple chatbots to sophisticated AI agents that can reason, plan, and execute complex tasks autonomously. This guide explores the architecture, patterns, and best practices for building production-ready AI agents.

AI Robot Photo by Alex Knight on Unsplash

What Are AI Agents?

An AI agent is a system that can:

  • Perceive: Understand context and user intent
  • Reason: Break down complex problems into steps
  • Plan: Create actionable sequences
  • Act: Execute tasks using tools and APIs
  • Learn: Improve from feedback and outcomes

Unlike traditional chatbots that simply respond to queries, agents take initiative, make decisions, and accomplish goals.

Agent Architecture

┌─────────────────────────────────────────────────────────────┐
│                        AI Agent                              │
├─────────────────────────────────────────────────────────────┤
│  ┌─────────────┐  ┌─────────────┐  ┌─────────────────────┐ │
│  │   Memory    │  │  Reasoning  │  │   Tool Interface    │ │
│  │             │  │   Engine    │  │                     │ │
│  │ • Short-term│  │ • Planning  │  │ • API Calls         │ │
│  │ • Long-term │  │ • Reflection│  │ • Code Execution    │ │
│  │ • Working   │  │ • Decision  │  │ • Database Access   │ │
│  └──────┬──────┘  └──────┬──────┘  └──────────┬──────────┘ │
│         │                │                     │            │
│         └────────────────┼─────────────────────┘            │
│                          │                                   │
│                  ┌───────┴───────┐                          │
│                  │    LLM Core   │                          │
│                  │ (GPT/Claude)  │                          │
│                  └───────────────┘                          │
└─────────────────────────────────────────────────────────────┘

The ReAct Pattern

The most effective agent pattern combines Reasoning and Acting:

from anthropic import Anthropic

class ReActAgent:
    def __init__(self, tools: list[Tool]):
        self.client = Anthropic()
        self.tools = {tool.name: tool for tool in tools}
        self.max_iterations = 10
    
    def run(self, task: str) -> str:
        messages = [{"role": "user", "content": task}]
        
        for i in range(self.max_iterations):
            response = self.client.messages.create(
                model="claude-sonnet-4-20250514",
                max_tokens=4096,
                system=self._build_system_prompt(),
                messages=messages,
                tools=self._format_tools()
            )
            
            # Check for final answer
            if response.stop_reason == "end_turn":
                return self._extract_answer(response)
            
            # Process tool calls
            if response.stop_reason == "tool_use":
                tool_results = self._execute_tools(response)
                messages.append({"role": "assistant", "content": response.content})
                messages.append({"role": "user", "content": tool_results})
        
        return "Max iterations reached"
    
    def _execute_tools(self, response) -> list:
        results = []
        for block in response.content:
            if block.type == "tool_use":
                tool = self.tools[block.name]
                result = tool.execute(**block.input)
                results.append({
                    "type": "tool_result",
                    "tool_use_id": block.id,
                    "content": str(result)
                })
        return results

Memory Systems

Effective agents need sophisticated memory:

Short-term Memory (Conversation Context)

class ConversationMemory:
    def __init__(self, max_tokens: int = 8000):
        self.messages = []
        self.max_tokens = max_tokens
    
    def add(self, role: str, content: str):
        self.messages.append({"role": role, "content": content})
        self._trim_if_needed()
    
    def _trim_if_needed(self):
        while self._count_tokens() > self.max_tokens:
            # Keep system message, remove oldest user/assistant pairs
            if len(self.messages) > 2:
                self.messages.pop(1)

Long-term Memory (Vector Store)

from chromadb import Client
import hashlib

class LongTermMemory:
    def __init__(self):
        self.client = Client()
        self.collection = self.client.create_collection("agent_memory")
    
    def store(self, content: str, metadata: dict = None):
        doc_id = hashlib.md5(content.encode()).hexdigest()
        self.collection.add(
            documents=[content],
            ids=[doc_id],
            metadatas=[metadata or {}]
        )
    
    def recall(self, query: str, n_results: int = 5) -> list[str]:
        results = self.collection.query(
            query_texts=[query],
            n_results=n_results
        )
        return results["documents"][0]

Neural Network Photo by Growtika on Unsplash

Tool Design Patterns

Structured Tool Definitions

from pydantic import BaseModel, Field
from typing import Callable

class Tool(BaseModel):
    name: str
    description: str
    parameters: dict
    function: Callable
    
    class Config:
        arbitrary_types_allowed = True
    
    def execute(self, **kwargs):
        return self.function(**kwargs)

# Example: Web Search Tool
def web_search(query: str, num_results: int = 5) -> list[dict]:
    """Search the web and return results."""
    # Implementation with search API
    pass

search_tool = Tool(
    name="web_search",
    description="Search the web for current information. Use for recent events, facts, or research.",
    parameters={
        "type": "object",
        "properties": {
            "query": {"type": "string", "description": "Search query"},
            "num_results": {"type": "integer", "default": 5}
        },
        "required": ["query"]
    },
    function=web_search
)

Tool Categories

CategoryExamplesUse Case
InformationWeb search, Wikipedia, News APIResearch, fact-checking
ComputationCalculator, Code interpreterMath, data analysis
IntegrationEmail, Calendar, CRMWorkflow automation
File SystemRead, write, list filesDocument processing
DatabaseSQL queries, vector searchData retrieval

Planning Strategies

Hierarchical Task Decomposition

class PlanningAgent:
    def create_plan(self, goal: str) -> list[dict]:
        prompt = f"""
        Break down this goal into actionable steps:
        Goal: {goal}
        
        Return a JSON array of steps, each with:
        - step_number: int
        - action: string (what to do)
        - tool: string (which tool to use, or "none")
        - dependencies: list[int] (which steps must complete first)
        - expected_output: string
        """
        
        response = self.client.messages.create(
            model="claude-sonnet-4-20250514",
            max_tokens=2000,
            messages=[{"role": "user", "content": prompt}]
        )
        
        return json.loads(response.content[0].text)
    
    def execute_plan(self, plan: list[dict]) -> dict:
        results = {}
        completed = set()
        
        while len(completed) < len(plan):
            for step in plan:
                if step["step_number"] in completed:
                    continue
                
                # Check dependencies
                deps = set(step["dependencies"])
                if not deps.issubset(completed):
                    continue
                
                # Execute step
                result = self._execute_step(step, results)
                results[step["step_number"]] = result
                completed.add(step["step_number"])
        
        return results

Error Handling and Recovery

Robust agents need graceful failure handling:

class ResilientAgent:
    def execute_with_retry(self, tool_call: dict, max_retries: int = 3):
        for attempt in range(max_retries):
            try:
                result = self.tools[tool_call["name"]].execute(**tool_call["input"])
                return {"success": True, "result": result}
            except Exception as e:
                if attempt == max_retries - 1:
                    return self._handle_failure(tool_call, e)
                
                # Ask LLM to fix the call
                fixed_call = self._request_fix(tool_call, str(e))
                tool_call = fixed_call
    
    def _request_fix(self, original_call: dict, error: str) -> dict:
        prompt = f"""
        This tool call failed:
        {json.dumps(original_call)}
        
        Error: {error}
        
        Please provide a corrected tool call that might work.
        """
        # Get LLM to suggest fix
        ...

Multi-Agent Systems

For complex tasks, orchestrate multiple specialized agents:

class AgentOrchestrator:
    def __init__(self):
        self.agents = {
            "researcher": ResearchAgent(),
            "writer": WritingAgent(),
            "coder": CodingAgent(),
            "reviewer": ReviewAgent()
        }
    
    async def delegate(self, task: str) -> str:
        # Determine which agents needed
        plan = await self._create_delegation_plan(task)
        
        results = {}
        for step in plan:
            agent = self.agents[step["agent"]]
            context = self._gather_context(step, results)
            result = await agent.run(step["task"], context)
            results[step["id"]] = result
        
        return self._synthesize_results(results)

Observability and Debugging

Production agents need comprehensive logging:

import structlog
from opentelemetry import trace

class ObservableAgent:
    def __init__(self):
        self.logger = structlog.get_logger()
        self.tracer = trace.get_tracer(__name__)
    
    def run(self, task: str):
        with self.tracer.start_as_current_span("agent_run") as span:
            span.set_attribute("task", task[:100])
            
            self.logger.info("agent_started", task=task)
            
            try:
                result = self._execute(task)
                span.set_attribute("success", True)
                self.logger.info("agent_completed", result_length=len(result))
                return result
            except Exception as e:
                span.set_attribute("success", False)
                span.record_exception(e)
                self.logger.error("agent_failed", error=str(e))
                raise

Security Considerations

Agents with tool access require careful security:

  1. Sandboxing: Execute code in isolated environments
  2. Permission Scoping: Limit tool access based on context
  3. Rate Limiting: Prevent runaway API calls
  4. Input Validation: Sanitize all tool inputs
  5. Audit Logging: Track all agent actions
class SecureAgent:
    def __init__(self, permissions: set[str]):
        self.permissions = permissions
    
    def can_use_tool(self, tool_name: str) -> bool:
        required = self.tools[tool_name].required_permissions
        return required.issubset(self.permissions)
    
    def execute_tool(self, tool_name: str, **kwargs):
        if not self.can_use_tool(tool_name):
            raise PermissionError(f"Agent lacks permission for {tool_name}")
        
        # Validate inputs
        self._validate_inputs(tool_name, kwargs)
        
        # Execute in sandbox
        return self._sandboxed_execute(tool_name, kwargs)

Conclusion

Building AI agents is both an art and a science. The key principles:

  • Start Simple: Begin with ReAct, add complexity as needed
  • Design Good Tools: Clear descriptions, validated inputs
  • Implement Memory: Both short-term and long-term
  • Plan for Failure: Retry logic, graceful degradation
  • Monitor Everything: Logs, traces, metrics

The future of software is agentic. These systems will increasingly handle complex workflows, make decisions, and act on our behalf. Understanding how to build them well is essential for every developer.


What will you build with AI agents?

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