C# SDK MCP — 사용 사례, 설치 & 라이브 데모

왜 쓰나요

핵심 기능

First-party, co-maintained with Microsoft
Attribute-based tool registration — ASP.NET-style
Native DI, IHostedService, ILogger integration
Stdio + HTTP/SSE transports out of the box

라이브 데모

실제 사용 모습

csharp-sdk.replay ▶ 준비됨

0/0

설치

클라이언트 선택

~/Library/Application Support/Claude/claude_desktop_config.json · Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "csharp-sdk": {
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "./MyMcpServer"
      ]
    }
  }
}

Claude Desktop → Settings → Developer → Edit Config 열기. 저장 후 앱 재시작.

~/.cursor/mcp.json · .cursor/mcp.json

{
  "mcpServers": {
    "csharp-sdk": {
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "./MyMcpServer"
      ]
    }
  }
}

Cursor는 Claude Desktop과 동일한 mcpServers 스키마 사용. 프로젝트 설정이 전역보다 우선.

VS Code → Cline → MCP Servers → Edit

{
  "mcpServers": {
    "csharp-sdk": {
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "./MyMcpServer"
      ]
    }
  }
}

Cline 사이드바의 MCP Servers 아이콘 클릭 후 "Edit Configuration" 선택.

~/.codeium/windsurf/mcp_config.json

{
  "mcpServers": {
    "csharp-sdk": {
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "./MyMcpServer"
      ]
    }
  }
}

Claude Desktop과 같은 형식. Windsurf 재시작 후 적용.

~/.continue/config.json

{
  "mcpServers": [
    {
      "name": "csharp-sdk",
      "command": "dotnet",
      "args": [
        "run",
        "--project",
        "./MyMcpServer"
      ]
    }
  ]
}

Continue는 맵이 아닌 서버 오브젝트 배열 사용.

~/.config/zed/settings.json

{
  "context_servers": {
    "csharp-sdk": {
      "command": {
        "path": "dotnet",
        "args": [
          "run",
          "--project",
          "./MyMcpServer"
        ]
      }
    }
  }
}

context_servers에 추가. 저장 시 Zed가 핫 리로드.

claude mcp add csharp-sdk -- dotnet run --project ./MyMcpServer

한 줄 명령. claude mcp list로 확인, claude mcp remove로 제거.

사용 사례

실전 활용법: C# SDK

Build an MCP server in .NET that exposes your existing services

👤 C#/.NET engineers with internal APIs ⏱ ~45 min intermediate

언제 쓸까: You're on .NET and want to expose business logic to agents without a rewrite.

사전 조건

.NET 8+ SDK — dotnet --version

흐름

Create the project

dotnet new console -n MyMcpServer. Add ModelContextProtocol NuGet. Use the minimal hosting template for MCP.✓ 복사됨

→ csproj + Program.cs with MCP hosted service
Add a tool

Create a static class with [McpServerToolType]. Add a method GetOrder(string id) decorated with [McpServerTool(Description="...")] that calls my existing OrderService via DI.✓ 복사됨

→ Tool compiles, description comes from attribute
Test with the inspector

Run the server as stdio. Launch the MCP Inspector via npx @modelcontextprotocol/inspector dotnet run. Call GetOrder.✓ 복사됨

→ Tool invocation returns order JSON

결과: A compiled, typed MCP server reusing your existing .NET services and DI container.

함정

Tool methods that are instance methods on a class need DI to work — Register the owning class in the ServiceCollection; the SDK resolves through DI
Async methods without proper cancellation tokens hang at shutdown — Accept CancellationToken ct as the last parameter on every tool — SDK injects it

Build a .NET console app that uses MCP servers

👤 C# devs building internal automation ⏱ ~30 min intermediate

언제 쓸까: You want deterministic .NET code (not an LLM loop) that calls MCP servers — e.g., a scheduled job that uses github + filesystem MCPs.

흐름

Add the client package

Create a console app. Reference ModelContextProtocol client. Add a config pointing at a stdio server (e.g. npx -y @modelcontextprotocol/server-github).✓ 복사됨

→ Client builds
Connect and call

Start the client, list tools, call list_repositories with my org name. Print the result.✓ 복사됨

→ Repos printed to console
Wrap as a scheduled job

Turn this into a Worker Service that runs nightly. Log metrics via ILogger.✓ 복사됨

→ Worker runs via dotnet run and schedules cleanly

결과: MCP as a library, not just a chat plugin — works inside any .NET process.

함정

Stdio servers take time to start, first call times out — Initialize the client at app startup and reuse; don't spawn per-call

Serve an MCP endpoint from an ASP.NET Core app

👤 .NET platform engineers ⏱ ~60 min advanced

언제 쓸까: You want the MCP server hosted inside an existing ASP.NET Core service, behind the same auth and ingress.

사전 조건

Existing ASP.NET Core app or willingness to start one — dotnet new web

흐름

Add MCP services + endpoint

In Program.cs, builder.Services.AddMcpServer().WithToolsFromAssembly(). Then app.MapMcp('/mcp').✓ 복사됨

→ /mcp endpoint responds to SSE handshake
Share auth with the rest of the app

Put the /mcp endpoint behind my existing JWT bearer auth middleware. Verify unauth'd requests get 401.✓ 복사됨

→ 401 unauth, 200 auth
Deploy and connect

Deploy. Wire a teammate's Claude Desktop via mcp-remote https://myapp.com/mcp with their JWT.✓ 복사됨

→ Team members see tools

결과: MCP alongside your existing API in one deploy with one auth story.

함정

Kestrel buffers SSE responses behind a reverse proxy — Disable response buffering; ensure IIS/nginx/Cloudflare in front also disable buffering for /mcp

함께 쓰기: cloud-run

조합

다른 MCP와 조합해 10배 효율

csharp-sdk + cloud-run

Deploy .NET MCP server on Cloud Run alongside other microservices

Containerize my .NET MCP server (mcr.microsoft.com/dotnet/aspnet base), deploy to Cloud Run with a min-instance=1 for cold-start mitigation.✓ 복사됨

csharp-sdk + fastmcp

Comparison for polyglot shops — different SDKs, same protocol

Our team has both Python and .NET services. Use FastMCP for Python APIs and csharp-sdk for .NET APIs — both behind one ContextForge gateway.✓ 복사됨

도구

이 MCP가 노출하는 것

도구	입력	언제 호출	비용
[McpServerToolType]	attribute on a class	Mark classes whose methods should be exposed	free
[McpServerTool(Description)]	attribute on a method	Each method you want agents to call	free
AddMcpServer() / WithToolsFromAssembly()	fluent builder	Program.cs at startup	free
MapMcp('/path')	ASP.NET endpoint	ASP.NET hosting only	free
IMcpClient	stdio or SSE transport config	Client-side usage	free

비용 및 제한

운영 비용

API 쿼터: None — this is an SDK
호출당 토큰: No framework overhead beyond MCP protocol
금액: Free, MIT licensed
팁: Use .NET's built-in logging and HealthChecks to catch problems before they balloon in prod

보안

권한, 시크릿, 파급범위

자격 증명 저장: Standard .NET: user-secrets for dev, environment variables or Key Vault for prod

데이터 외부 송신: Whatever your tools reach

문제 해결

자주 발생하는 오류와 해결

Tool not appearing in inspector

WithToolsFromAssembly() only scans the executing assembly. For tools in referenced libraries, pass the Assembly explicitly: WithTools(typeof(MyTools).Assembly).

DI can't resolve my service in a tool method

Tool types must be registered in the container. Add builder.Services.AddScoped<OrderService>() before AddMcpServer.

ASP.NET MapMcp returns 404

You mapped after app.Run() — move MapMcp before Run. Also check the path doesn't conflict with other endpoints.

JSON serialization fails on enums

SDK uses System.Text.Json; add [JsonStringEnumConverter] on your enums or configure globally.

대안

C# SDK 다른 것과 비교

대안	언제 쓰나	단점/장점
FastMCP (Python)	You're OK picking up Python — richer example ecosystem	Different language; team skill dependent
TypeScript MCP SDK	Node / TS shop	Similar DX, language choice

C# SDK

왜 쓰나요

핵심 기능

라이브 데모

실제 사용 모습

설치

클라이언트 선택

사용 사례

실전 활용법: C# SDK

Build an MCP server in .NET that exposes your existing services

사전 조건

흐름

함정

Build a .NET console app that uses MCP servers

흐름

함정

Serve an MCP endpoint from an ASP.NET Core app

사전 조건

흐름

함정

조합

다른 MCP와 조합해 10배 효율

도구

이 MCP가 노출하는 것

비용 및 제한

운영 비용

보안

권한, 시크릿, 파급범위

문제 해결

자주 발생하는 오류와 해결

대안

C# SDK 다른 것과 비교

더 보기

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