1# Azure OpenAI — .NET SDK Quick Reference
2 
3> Condensed from **azure-ai-openai-dotnet**. Full patterns (function calling, structured outputs, RAG with Search)
4> in the **azure-ai-openai-dotnet** plugin skill if installed.
5 
6## Install
7```bash
8dotnet add package Azure.AI.OpenAI
9```
10 
11## Quick Start
12```csharp
13using Azure.AI.OpenAI;
14using OpenAI.Chat;
15var azureClient = new AzureOpenAIClient(new Uri(endpoint), credential);
16ChatClient chatClient = azureClient.GetChatClient("gpt-4o-mini");
17```
18 
19## Non-Obvious Patterns
20- Client hierarchy: `AzureOpenAIClient.GetChatClient()` / `GetEmbeddingClient()` / `GetImageClient()` / `GetAudioClient()`
21- Reasoning models (o1): use `DeveloperChatMessage` instead of `SystemChatMessage`, set `ReasoningEffortLevel`
22- RAG: `#pragma warning disable AOAI001` then `options.AddDataSource(new AzureSearchChatDataSource{...})`
23- Structured outputs: `ChatResponseFormat.CreateJsonSchemaFormat(...)`
24 
25## Best Practices
261. Use Entra ID in production — avoid API keys
272. Reuse client instances — create once, share across requests
283. Handle rate limits — implement exponential backoff for 429 errors
294. Stream for long responses — use `CompleteChatStreamingAsync`
305. Set appropriate timeouts for long completions
316. Use structured outputs for consistent response format
327. Monitor token usage via `completion.Usage` for cost management
338. Validate tool call arguments before execution
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