Building an AI agent on Azure in 2026 means choosing between three serious frameworks — and each one is genuinely good for a different use case.
This is not a "just use LangChain" or "just use Microsoft's stuff" situation. The right choice depends on your team, your existing stack, and how much control you need over execution.
What Is an AI Agent?
An agent is an LLM connected to tools. Instead of just answering a question, it can take actions:
Search a knowledge base
Call an API
Write a file
Execute code
Trigger a workflow
Agents follow a loop: think → choose a tool → observe the result → think again → repeat until done.
User:"Find the top 3 open support tickets and summarize their status"Agent loop:Step1:Use search_tickets tool → returns 50 tickets
Step2:Use filter_tickets tool → filters to "open" status
Step3:Use sort_tickets tool → sorts by priority
Step4:Selects top 3 tickets
Step5:Uses summarize tool on each
Step6:Returns compiled summary to user
Without agents, this requires writing explicit orchestration code. With agents, the LLM figures out the sequence.
Option 1: Azure AI Agent Service
Microsoft's fully managed agent runtime. You define tools and agents via REST API or SDK; Microsoft manages execution, memory, threading, and state.
When to use:
You want zero infrastructure management
Your tools are simple (function calling, code interpreter, file search)
You need per-conversation thread persistence without managing state yourself
You're already in the Azure AI Foundry ecosystem
Creating an agent:
from azure.ai.projects import AIProjectClient
from azure.ai.projects.models import CodeInterpreterTool, FileSearchTool
from azure.identity import DefaultAzureCredential
project_client = AIProjectClient.from_connection_string( conn_str="eastus.api.azureml.ms;subscription-id;resource-group;workspace", credential=DefaultAzureCredential())agent = project_client.agents.create_agent( model="gpt-4o", name="azure-support-agent", instructions="""You are an Azure infrastructure support agent.
Help users diagnose and resolve Azure networking and AI deployment issues.
Always cite the specific resource or configuration that needs to change.""", tools=[ FileSearchTool().definitions,# search uploaded documents CodeInterpreterTool().definitions,# run Python for analysis])
Running a conversation:
# Each conversation is a "thread"thread = project_client.agents.create_thread()# Add user messageproject_client.agents.create_message( thread_id=thread.id, role="user", content="My Azure OpenAI deployments in eastus are returning 503 errors")# Run the agentrun = project_client.agents.create_and_process_run( thread_id=thread.id, assistant_id=agent.id)# Get the responsemessages = project_client.agents.list_messages(thread_id=thread.id)answer = messages.get_last_message_by_role("assistant")
What you get free: Thread persistence, automatic tool execution, built-in file search with Azure AI Search, code interpreter sandboxing.
What you give up: Fine-grained control over the agent loop. You can't interrupt mid-execution or inject context between steps.
Option 2: Semantic Kernel
Microsoft's open-source SDK for building AI applications. Works in Python and C#. Designed for enterprise integration — connects LLMs to existing enterprise systems.
When to use:
Your team is .NET/C#-first (SK was built for this)
You need to integrate AI into an existing enterprise application
You want plugin architecture that mirrors your existing service structure
You need fine-grained control over planning and execution
Defining a plugin:
from semantic_kernel import Kernel
from semantic_kernel.functions import kernel_function
from semantic_kernel.connectors.ai.open_ai import AzureChatCompletion
kernel = Kernel()kernel.add_service( AzureChatCompletion( deployment_name="gpt-4o", endpoint="https://yourresource.openai.azure.com", api_key="..."))classAzureResourcePlugin:@kernel_function(description="Get the status of an Azure resource by name")asyncdefget_resource_status(self, resource_name:str)->str:# Call Azure Resource Manager APIreturnf"Resource {resource_name}: Running (last checked 2m ago)"@kernel_function(description="Restart an Azure resource")asyncdefrestart_resource(self, resource_name:str)->str:# Call Azure Resource Manager APIreturnf"Restart initiated for {resource_name}"kernel.add_plugin(AzureResourcePlugin(), plugin_name="AzureResources")
Running an agent:
from semantic_kernel.agents import ChatCompletionAgent
from semantic_kernel.contents import ChatHistory
agent = ChatCompletionAgent( kernel=kernel, name="azure-ops-agent", instructions="You are an Azure operations agent. Use available plugins to help users manage their Azure resources.")history = ChatHistory()history.add_user_message("Check the status of my API service and restart it if it's unhealthy")asyncfor message in agent.invoke(history=history):print(message.content)
What you get: Full control over planning steps, easy plugin registration, enterprise-grade streaming and error handling, excellent observability via OpenTelemetry.
What you give up: More boilerplate than Agent Service. You manage state and threading yourself.
Option 3: LangChain
The most widely used AI framework outside Microsoft. Extensive ecosystem of pre-built tools, retrievers, and agent patterns.
When to use:
Your team has existing LangChain expertise
You need the broadest ecosystem (hundreds of pre-built integrations)
You're prototyping quickly and want to move fast
You need multi-agent patterns (LangGraph)
Creating an agent:
from langchain_openai import AzureChatOpenAI
from langchain.agents import create_tool_calling_agent, AgentExecutor
from langchain.tools import tool
from langchain_core.prompts import ChatPromptTemplate
llm = AzureChatOpenAI( azure_deployment="gpt-4o", azure_endpoint="https://yourresource.openai.azure.com", api_key="...", api_version="2024-08-01-preview")@tooldefsearch_azure_docs(query:str)->str:"""Search Azure documentation for a given query"""# Call Azure AI Searchreturn"Search results..."@tooldefget_azure_status(service:str)->str:"""Get current Azure service health status"""returnf"{service}: Healthy"tools =[search_azure_docs, get_azure_status]prompt = ChatPromptTemplate.from_messages([("system","You are an Azure support agent. Use the tools to help users."),("human","{input}"),("placeholder","{agent_scratchpad}"),])agent = create_tool_calling_agent(llm, tools, prompt)executor = AgentExecutor(agent=agent, tools=tools, verbose=True)result = executor.invoke({"input":"What are the current limits for Azure OpenAI?"})
What you get: Fast prototyping, massive ecosystem, LangGraph for complex multi-agent workflows.
What you give up: Less enterprise polish than SK. LangChain versioning is aggressive — upgrades often break things.
Comparison Matrix
Factor
AI Agent Service
Semantic Kernel
LangChain
Infrastructure management
None (managed)
Self-managed
Self-managed
Control over execution
Low
High
High
.NET/C# support
SDK available
Native
Limited
Python support
SDK available
Good
Excellent
Enterprise integrations
Azure-native
Microsoft-first
Broad ecosystem
Multi-agent support
Limited
Good
Excellent (LangGraph)
Learning curve
Low
Medium
Medium
Production stability
High
High
Medium (rapid releases)
State management
Built-in
Manual
Manual
Open source
SDK is OSS
Yes
Yes
Decision Guide
Use Azure AI Agent Service when:
Greenfield project, want fast shipping
Your tools are file search and code execution
You don't need cross-agent communication
Azure AI Foundry is your platform
Use Semantic Kernel when:
Your team builds in .NET or Python
You're integrating AI into an existing enterprise application
You need predictable, well-tested enterprise behavior
You want Microsoft support and roadmap alignment
Use LangChain when:
You need multi-agent orchestration (LangGraph)
You're using non-Azure AI providers alongside Azure
Your team has strong existing LangChain knowledge
You need an integration that doesn't exist in SK or Agent Service
For most new enterprise Azure AI projects in 2026, Semantic Kernel is the lowest-risk choice with the best long-term support story. LangChain is the right call if your use case needs LangGraph's multi-agent patterns or a specific third-party integration.