6 Types of LLMs Used in AI Agents: The Blueprint for Production-Ready Systems + Video

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Introduction

Building AI agents is not about choosing one model; it’s about designing the right system architecture that orchestrates multiple models to solve diverse problems. Many organizations fail in their AI initiatives not because they lack powerful models, but because they underestimate the infrastructure required around those models—including retrieval, tool access, workflow logic, guardrails, and monitoring. The shift from answering questions to completing tasks requires a multi-model ecosystem where GPT-style language models, Vision-Language Models (VLMs), Small Language Models (SLMs), reasoning models, and action models work together seamlessly within production-grade execution layers.

Learning Objectives

  • Understand the six distinct types of LLMs used in AI agents and their specific use cases.
  • Learn how to design system architecture that integrates multiple models with RAG pipelines, APIs, and workflow automation.
  • Master practical implementation techniques including prompt engineering, tool-calling, and production monitoring for AI agent deployments.
  1. GPT-Style Models: The Foundation for Language and Reasoning

GPT-style models form the cognitive backbone of most AI agents, excelling at natural language understanding, generation, and complex reasoning tasks. These models are ideal for conversational interfaces, content generation, summarization, and few-shot learning scenarios where nuanced language comprehension is critical.

Step-by-Step Implementation Guide

To leverage GPT-style models effectively in your AI agent:

Step 1: Environment Setup

 Install the OpenAI Python library
pip install openai python-dotenv

Set up your API key
export OPENAI_API_KEY="your-api-key-here"

Step 2: Basic Chat Completion with System Prompt

import openai

response = openai.ChatCompletion.create(
model="gpt-4",
messages=[
{"role": "system", "content": "You are a helpful AI assistant."},
{"role": "user", "content": "Explain the concept of RAG in 3 sentences."}
],
temperature=0.7,
max_tokens=150
)
print(response.choices[bash].message.content)

Step 3: Few-Shot Prompting for Specialized Tasks

messages = [
{"role": "system", "content": "You classify customer support tickets."},
{"role": "user", "content": "Ticket: 'My account is locked and I need access urgently.'"},
{"role": "assistant", "content": "Priority: High, Category: Account Access"},
{"role": "user", "content": "Ticket: 'Can you update my email address?'"}
]
 Add your classification logic here

Step 4: Implement Chain-of-Thought Reasoning

def solve_with_cot(query):
prompt = f"""
Let's solve this step by step:
Question: {query}
Step 1: Understand the problem
Step 2: Break down requirements
Step 3: Generate solution

Final Answer:
"""
 Process the prompt with your chosen model

Windows PowerShell Commands

 Set environment variable
$env:OPENAI_API_KEY="your-api-key-here"

Install dependencies
pip install openai python-dotenv

Run Python script
python agent.py

Linux/Bash Commands

 One-liner to test API connectivity
curl https://api.openai.com/v1/models \
-H "Authorization: Bearer $OPENAI_API_KEY"

2. Vision-Language Models (VLMs): Enabling Multimodal Understanding

VLMs integrate visual and textual processing, allowing AI agents to interpret images, diagrams, documents, and visual data alongside text. These models are essential for applications requiring document understanding, visual QA, and image analysis.

Step-by-Step VLM Implementation

Step 1: Install Required Libraries

 Install the necessary packages
pip install transformers torch pillow langchain

Step 2: Load and Use a VLM like LLaVA

from transformers import AutoProcessor, LlavaForConditionalGeneration
from PIL import Image
import requests

Load model and processor
model = LlavaForConditionalGeneration.from_pretrained("llava-hf/llava-1.5-7b-hf")
processor = AutoProcessor.from_pretrained("llava-hf/llava-1.5-7b-hf")

Process image and text
image = Image.open("document_screenshot.png")
prompt = "Extract all text and describe the layout of this document."

inputs = processor(prompt, image, return_tensors="pt")
output = model.generate(inputs, max_new_tokens=200)
response = processor.decode(output[bash], skip_special_tokens=True)

Step 3: Integrate with Document AI Workflows

def process_document_with_vlm(file_path):
"""Extract structured information from documents using VLM"""
image = Image.open(file_path)
prompt = """
Please analyze this document and extract:
1. Document type (invoice, contract, report)
2. Key dates and amounts
3. Entity names
4. content
"""
 Process with VLM
 Return structured output
  1. Small Language Models (SLMs): Optimizing for Speed and Cost

SLMs like Phi, Gemma, and Mistral-7B offer faster inference with lower computational costs, making them suitable for real-time applications, edge devices, and scenarios where latency matters more than maximum accuracy.

Step-by-Step SLM Deployment

Step 1: Install Ollama for Local Model Management

 Install Ollama
curl -fsSL https://ollama.com/install.sh | sh

Pull a small language model
ollama pull mistral:7b
 OR
ollama pull phi3:mini

Step 2: Start the Model Server

 Run the model with API support
ollama run mistral:7b --api

Step 3: Implement Fast Inference Pipeline

import requests
import json

def query_slm(prompt):
response = requests.post(
"http://localhost:11434/api/generate",
json={"model": "mistral:7b", "prompt": prompt}
)
return response.json()["response"]

Use for fast classification tasks
category = query_slm(
"Classify this email: 'Please reset my password' as Technical/Non-Technical"
)

Step 4: Quantization for Deployment

 Use llama.cpp for quantized models
git clone https://github.com/ggerganov/llama.cpp
cd llama.cpp
make

Convert and quantize model
./convert.py models/mistral-7b/
./quantize.py models/mistral-7b/ggml-model-f16.gguf

4. Reasoning Models: Planning and Multi-Step Logic

Reasoning models specialize in complex planning, multi-step problem-solving, and logical deduction. These models are critical for agents that need to create execution plans, break down complex tasks, and validate solutions.

Step-by-Step Reasoning Implementation

Step 1: Define the Agent Structure

class ReasoningAgent:
def <strong>init</strong>(self, model="gpt-4", tools=[]):
self.model = model
self.tools = tools
self.memory = []

def plan_task(self, task_description):
"""Generate a multi-step execution plan"""
plan_prompt = f"""
You are a planning agent. Generate a step-by-step plan for:
Task: {task_description}

Format the plan as a numbered list with clear actions.
Include dependencies between steps.
"""
 Process through reasoning model
return plan

Step 2: Implement the Plan-Execute-Validate Loop

def execute_with_reasoning(agent, task):
 Phase 1: Plan
plan = agent.plan_task(task)

Phase 2: Execute each step
results = []
for step in plan:
result = agent.execute_step(step)
results.append(result)

Phase 3: Validate intermediate results
if not agent.validate_step(step, result):
plan = agent.replan(task, results)
break

Phase 4: Final validation
return agent.validate_final_output(results)
  1. Action Models: Tool Use, APIs, and Workflow Execution

Action models are specifically fine-tuned for function calling and API interactions. They understand how to invoke external tools, format API requests, and orchestrate complex workflow executions.

Step-by-Step Tool-Calling Implementation

Step 1: Define Tools and Functions

 Define a tool for API interaction
tools = [
{
"name": "get_weather",
"description": "Get current weather data for a location",
"parameters": {
"type": "object",
"properties": {
"location": {"type": "string", "description": "City name"}
},
"required": ["location"]
}
},
{
"name": "send_email",
"description": "Send an email through the system",
"parameters": {
"type": "object",
"properties": {
"to": {"type": "string"},
"subject": {"type": "string"},
"body": {"type": "string"}
},
"required": ["to", "subject", "body"]
}
}
]

Step 2: Implement Action Functions

def get_weather(location):
import requests
response = requests.get(
f"https://api.weather.com/v1/current/{location}",
headers={"Authorization": "Bearer YOUR_API_KEY"}
)
return response.json()

def send_email(to, subject, body):
 Email sending logic using SMTP or email service
import smtplib
 Configuration and sending logic here
return {"status": "sent", "to": to}

Step 3: Build the Action-Agent Integration

def process_action_request(user_input, tools, action_functions):
 Step 1: Send to model with tool descriptions
response = openai.ChatCompletion.create(
model="gpt-4-turbo-preview",
messages=[{"role": "user", "content": user_input}],
tools=tools,
tool_choice="auto"
)

Step 2: Parse tool call response
tool_calls = response.choices[bash].message.tool_calls
for call in tool_calls:
function_name = call.function.name
arguments = json.loads(call.function.arguments)

Step 3: Execute the action
if function_name in action_functions:
result = action_functions<a href="arguments">function_name</a>
print(f"Action {function_name} executed with result: {result}")

Step 4: Workflow Automation with GitHub Actions

 .github/workflows/ai-agent.yml
name: AI Agent Workflow

on:
push:
branches: [bash]
schedule:
- cron: '0 /6   '  Run every 6 hours

jobs:
run-agent:
runs-on: ubuntu-latest
steps:
- uses: actions/checkout@v3
- name: Setup Python
uses: actions/setup-python@v4
with:
python-version: '3.10'
- name: Install Dependencies
run: pip install -r requirements.txt
- name: Run AI Agent
run: python agent_automation.py
env:
OPENAI_API_KEY: ${{ secrets.OPENAI_API_KEY }}

6. System Architecture: Designing Production-Ready AI Agents

The true value of AI agents emerges when multiple models work together inside a unified flow. Production architecture must include RAG pipelines for retrieval, workflow logic for orchestration, guardrails for safety, and comprehensive monitoring for reliability.

Step-by-Step Production Architecture Setup

Step 1: Setup RAG with ChromaDB

import chromadb
from chromadb.utils import embedding_functions

Initialize ChromaDB
client = chromadb.PersistentClient(path="./chroma_db")
collection = client.get_or_create_collection(
name="knowledge_base",
embedding_function=embedding_functions.OpenAIEmbeddingFunction()
)

Add documents to collection
collection.add(
documents=["Document 1 content here", "Document 2 content here"],
ids=["doc1", "doc2"],
metadatas=[{"source": "internal"}, {"source": "external"}]
)

Query with retrieval
results = collection.query(
query_texts=["User query here"],
n_results=3
)

Step 2: Implement Context Management

class ContextManager:
def <strong>init</strong>(self, max_tokens=4000):
self.history = []
self.max_tokens = max_tokens

def add_to_context(self, message, role="user"):
self.history.append({"role": role, "content": message})
self._truncate_context()

def _truncate_context(self):
 Calculate token usage and truncate if needed
current_tokens = self._count_tokens(self.history)
if current_tokens > self.max_tokens:
self.history = self.history[-5:]  Keep last 5 exchanges

Step 3: Build Guardrail Systems

def implement_guardrails(user_input, model_output):
 Safety checks
forbidden_patterns = [
r"password|secret|API_KEY",  Sensitive information
r"hack|exploit|crack",  Malicious intent
]

for pattern in forbidden_patterns:
if re.search(pattern, user_input, re.IGNORECASE):
return {"allowed": False, "reason": "Security policy violation"}

Content moderation
moderation_result = openai.Moderation.create(input=model_output)
if moderation_result.results[bash].flagged:
return {"allowed": False, "reason": "Content policy violation"}

return {"allowed": True}

Step 4: Monitoring and Logging with Prometheus

from prometheus_client import Counter, Histogram, start_http_server

Define metrics
requests_total = Counter('ai_agent_requests_total', 'Total requests processed')
request_latency = Histogram('ai_agent_request_latency_seconds', 'Request latency')
error_counter = Counter('ai_agent_errors_total', 'Total errors by type')

Start metrics server
start_http_server(8000)

Use in your agent
def process_with_monitoring(user_input):
requests_total.inc()
with request_latency.time():
try:
result = process_request(user_input)
return result
except Exception as e:
error_counter.labels(error_type=str(type(e).<strong>name</strong>)).inc()
raise

Step 5: Human Approval Workflow

def human_in_the_loop(decision, confidence_score):
if confidence_score < 0.8:
 Escalate to human
approval_request = {
"action": decision,
"confidence": confidence_score,
"requires_approval": True
}

Send notification via email/Slack
send_approval_notification(approval_request)

Wait for approval (async processing)
return {"status": "pending_approval", "id": generate_ticket_id()}
else:
return {"status": "automated", "action": decision}

Practical Deployment Considerations

 Deploy with Docker
docker build -t ai-agent-system .

Docker run with environment variables
docker run -d -p 8080:8080 \
-e OPENAI_API_KEY=$OPENAI_API_KEY \
-e CHROMA_DB_PATH=/data/chroma \
-v /path/to/data:/data \
ai-agent-system

What Undercode Say

  • Architecture Over Models: The most common failure point in AI agent projects isn’t the model choice but the lack of robust architecture. Organizations should spend 70% of their effort on designing the system around the model—including retrieval mechanisms, tool integrations, and production safeguards.

  • Multi-Model Strategy: Don’t fall into the trap of using one model for everything. A hybrid approach using GPT-style models for reasoning, SLMs for fast inference, and action models for tool use provides the best balance of performance, cost, and reliability. Companies like Services Ground demonstrate that layering models for specific tasks yields production-ready systems capable of supporting real business workflows.

The transition from AI demos to production systems requires a fundamental shift in thinking—from “which model should we use?” to “what system do we need to build around the model?” This architectural perspective enables AI agents to evolve from simple question-answering tools to task-completing assistants that can handle complex business workflows with appropriate guardrails and human oversight. The future of AI agent development lies not in model selection alone, but in orchestrating multiple specialized models within a unified, monitorable, and scalable production environment.

Prediction

  • +1 Enterprise adoption of multi-model architectures will accelerate as organizations realize that no single model can handle all tasks effectively, creating a new market for AI orchestration platforms.

  • +1 The rise of SLMs and quantized models will democratize AI agent deployment, enabling smaller organizations to implement sophisticated AI systems without massive infrastructure investments.

  • -1 Companies that fail to implement proper guardrails and monitoring systems will face significant regulatory and reputational risks as AI agents become more autonomous and integrated into critical business processes.

  • +1 The convergence of RAG, tool-calling, and workflow automation will create a new category of AI solutions that can replace entire departments for routine tasks, fundamentally changing how businesses operate.

  • -1 The complexity of managing multiple models and their interactions will create operational overhead, potentially leading to a “tool sprawl” problem similar to the early days of cloud adoption.

▶️ Related Video (82% Match):

https://www.youtube.com/watch?v=1D1-trjgywA

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