Claude Opus 4.5 Now in Azure AI Foundry: What .NET Developers Need to Know

TL;DR Anthropic’s Claude Opus 4.5 is now available in public preview in Microsoft Foundry, GitHub Copilot paid plans, and Microsoft Copilot Studio. Pricing drops to $5 per million input tokens and $25 per million output tokens—a 67% reduction from Opus 4.1. In early testing, Claude Opus 4.5 surpassed internal coding benchmarks while cutting token usage in half. For Azure-hosted .NET workloads, this means cheaper, faster agentic workflows without switching platforms.

The Strategic Win: Azure Gets Both GPT and Claude

For the first time, Azure is the only cloud providing access to both Claude and GPT frontier models to customers on one platform. This isn’t just vendor parity—it’s developer choice at scale. Anthropic is scaling its rapidly-growing Claude AI model on Microsoft Azure, powered by NVIDIA, which will broaden access to Claude and provide Azure enterprise customers with expanded model choice and new capabilities. What does this mean for you? If you’re building AI agents in Azure AI Foundry or GitHub Copilot, you can now benchmark Claude Opus 4.5 against GPT-5 variants in the same environment, using the same deployment infrastructure, without context-switching between clouds.

Performance & Cost: The Numbers That Matter

Opus 4.5 sets a new bar for coding, agentic workflows, and enterprise productivity: outperforming Sonnet 4.5 and Opus 4.1, at a more accessible price point. For engineers shipping production systems, two metrics stand out:

Token efficiency: Token usage cut in half compared to prior versions. Fewer tokens = lower latency and cost per inference.
Coding prowess: Claude Opus 4.5 scored higher on Anthropic’s most challenging internal engineering assessment than any human job candidate in the company’s history. For a typical enterprise running multi-agent orchestration across Azure, halving token usage translates directly to operational savings and faster response times—critical for real-time customer-facing agents.

What This Unlocks for .NET & Azure Builders

1. Agentic Workflows with Constraint Awareness

Opus 4.5 shows strong, real-world intelligence applying tools creatively within constraints. In testing, the model successfully navigated complex policy environments, such as airline change rules, chaining upgrades, downgrades, cancellations, and rebookings to optimize outcomes. For .NET developers building agents in Azure AI Foundry, this means Claude can now handle multi-step workflows—like orchestrating a deployment failure diagnosis, querying Azure DevOps logs, recommending a fix, and triggering a patch—all autonomously within your governance boundaries.

2. Model Router Flexibility

In Azure AI Foundry, the GPT-5 models are available via API and orchestrated by the model router. With Claude Opus 4.5 now available, you can configure model router to dynamically select Claude or GPT-5 based on task complexity, cost, or latency requirements—all from a single endpoint.

Example routing logic:

// Pseudo-code: Azure AI Foundry model router
var response = await modelRouter.CompleteAsync(
    prompt: userQuery,
    routingStrategy: RoutingStrategy.CostOptimized, // or PerformanceOptimized
    allowedModels: new[] { "gpt-5", "claude-opus-4-5" }
);

3. Tool Use & Skills Framework

With the Claude API, developers can define skills modular building blocks. Each skill is dynamically discovered, maximizing your agent’s context. Skills automate a workflow like generating reports, cleaning datasets, or assembling PowerPoint summaries and can be reused or chained with others. Within Microsoft Foundry, every Skill is governed, tracible, and version-controlled, ensuring reliability across teams and projects. In .NET, you can define reusable Skills that Claude orchestrates:

// Define a Skill for Azure DevOps integration
public class DeploymentDiagnosticSkill : IAgentSkill
{
    public async Task<string> DiagnoseFailureAsync(string deploymentId)
    {
        // Query Azure DevOps, analyze logs, return diagnosis
    }
}

// Claude agent invokes it autonomously
var diagnosis = await agent.InvokeSkillAsync<DeploymentDiagnosticSkill>();

Integration Checklist for Azure Engineers

Access: Opus 4.5 is now available in public preview in Microsoft Foundry, GitHub Copilot paid plans, and Microsoft Copilot Studio. Provision it via Azure AI Foundry portal or SDK.
Deployment: Use Azure AI Foundry services with OpenTelemetry instrumentation for monitoring, and compatibility with existing Microsoft development tools including Visual Studio Code through the AI Toolkit extension.
Cost baseline: Compare token usage before/after. With 50% token reduction, even a modest agent fleet sees immediate savings.
Governance: Azure customers will gain expanded choice in models and access to Claude-specific capabilities. Leverage Azure Policy to pre-approve Claude deployments alongside GPT models.

The Bigger Picture

Anthropic has committed to purchase $30 billion of Azure compute capacity and to contract additional compute capacity up to one gigawatt. This isn’t a one-off integration—it’s a long-term bet. Microsoft and Anthropic are aligned on making Azure the home for frontier reasoning, whether you choose Claude or OpenAI.

For .NET and Azure engineers shipping production AI systems, this means:

Stability: Multi-year commitment from both vendors.
Choice: No lock-in; compare models in the same environment.
Economics: Price pressure drives down costs for everyone.