C# MCP Server Publishing

Workflow

Step 1: Choose the publishing path

Both paths can optionally publish to the MCP Registry for discoverability.

Step 2a: NuGet publishing (stdio servers)

1. Configure .csproj with package properties:

<PropertyGroup>
  <PackAsTool>true</PackAsTool>
  <ToolCommandName>mymcpserver</ToolCommandName>
  <PackageId>YourUsername.MyMcpServer</PackageId>
  <Version>1.0.0</Version>
  <Authors>Your Name</Authors>
  <Description>MCP server for interacting with MyService</Description>
  <PackageLicenseExpression>MIT</PackageLicenseExpression>
  <PackageTags>mcp;modelcontextprotocol;ai;llm</PackageTags>
  <PackageReadmeFile>README.md</PackageReadmeFile>
</PropertyGroup>

<ItemGroup>
  <None Include="README.md" Pack="true" PackagePath="\" />
</ItemGroup>

2. Build and pack:

dotnet build -c Release
dotnet pack -c Release

3. Test locally before publishing:

dotnet tool install --global --add-source bin/Release/ YourUsername.MyMcpServer
mymcpserver --help          # verify it runs
dotnet tool uninstall --global YourUsername.MyMcpServer

4. Push to NuGet.org:

dotnet nuget push bin/Release/*.nupkg \
  --api-key YOUR_NUGET_API_KEY \
  --source https://api.nuget.org/v3/index.json

5. Verify — users configure in mcp.json:

{
  "servers": {
    "MyMcpServer": {
      "type": "stdio",
      "command": "dnx",
      "args": ["[email protected]", "--yes"]
    }
  }
}

For detailed NuGet packaging and trusted publishing setup, see references/nuget-packaging.md.

Step 2b: Docker containerization (HTTP servers)

1. Create Dockerfile:

FROM mcr.microsoft.com/dotnet/sdk:10.0 AS build
WORKDIR /src
COPY *.csproj ./
RUN dotnet restore
COPY . ./
RUN dotnet publish -c Release -o /app

FROM mcr.microsoft.com/dotnet/aspnet:10.0
WORKDIR /app
COPY --from=build /app .

# Non-root user for security
RUN adduser --disabled-password --gecos '' appuser
USER appuser

ENV ASPNETCORE_URLS=http://+:8080
EXPOSE 8080
HEALTHCHECK --interval=30s --timeout=3s --start-period=10s --retries=3 \
  CMD curl -f http://localhost:8080/health || exit 1
ENTRYPOINT ["dotnet", "MyMcpServer.dll"]

2. Build and test locally:

docker build -t mymcpserver:latest .
docker run -d -p 3001:8080 -e API_KEY=test-key --name mymcpserver mymcpserver:latest
curl http://localhost:3001/health

3. Push to container registry:

# Docker Hub
docker tag mymcpserver:latest <yourusername>/<mymcpserver>:1.0.0
docker push <yourusername>/<mymcpserver>:1.0.0

# Azure Container Registry
az acr login --name yourregistry
docker tag mymcpserver:latest <yourregistry>.azurecr.io/<mymcpserver>:1.0.0
docker push <yourregistry>.azurecr.io/<mymcpserver>:1.0.0

Step 3: Deploy to Azure (HTTP servers)

Azure Container Apps (recommended — serverless with auto-scaling):

az containerapp create \
  --name mymcpserver \
  --resource-group mygroup \
  --environment myenvironment \
  --image <yourregistry>.azurecr.io/<mymcpserver>:1.0.0 \
  --target-port 8080 \
  --ingress external \
  --min-replicas 0 \
  --max-replicas 10 \
  --secrets api-key=my-actual-api-key \
  --env-vars API_KEY=secretref:api-key

Azure App Service (traditional web hosting):

az webapp create \
  --name mymcpserver \
  --resource-group mygroup \
  --plan myplan \
  --deployment-container-image-name <yourregistry>.azurecr.io/<mymcpserver>:1.0.0

For detailed Azure deployment, see references/docker-azure.md.

Step 4: Publish to MCP Registry (optional)

List your server in the official MCP Registry for discoverability.

1. Install mcp-publisher:

# macOS/Linux
brew install mcp-publisher

# Or download from https://github.com/modelcontextprotocol/registry/releases

2. Create .mcp/server.json (or run mcp-publisher init to generate interactively):

{
  "$schema": "https://static.modelcontextprotocol.io/schemas/2025-12-11/server.schema.json",
  "name": "io.github.username/servername",
  "description": "Your server description",
  "version": "1.0.0",
  "packages": [{
    "registryType": "nuget",
    "registryBaseUrl": "https://api.nuget.org",
    "identifier": "YourUsername.MyMcpServer",
    "version": "1.0.0",
    "transport": { "type": "stdio" }
  }],
  "repository": {
    "url": "https://github.com/username/repo",
    "source": "github"
  }
}

Version consistency (critical): The root version, packages[].version, and <Version> in .csproj must all match. A mismatch causes registry validation failures or users downloading the wrong version.

3. Authenticate and publish:

mcp-publisher login github      # name must be io.github.<username>/... for GitHub auth
mcp-publisher publish

4. Verify:

curl "https://registry.modelcontextprotocol.io/v0.1/servers?search=io.github.<username>/<servername>"

For Registry details (namespace conventions, environment variables, CI/CD automation), see references/mcp-registry.md.

Step 5: Security checklist

• No hardcoded secrets — use environment variables or Key Vault
• HTTPS enabled for HTTP transport in production
• Health check endpoint implemented
• Input validation on all tool parameters
• Rate limiting considered for HTTP servers

Validation

• NuGet: Package installs and runs via dnx PackageId@version
• Docker: Container starts and health check passes
• Azure: Server is reachable and tools respond
• MCP Registry: Server appears at registry.modelcontextprotocol.io
• MCP client can connect and call tools on the deployed server

Common Pitfalls

Related Skills

• mcp-csharp-create — Create a new MCP server project
• mcp-csharp-debug — Running and interactive debugging
• mcp-csharp-test — Automated tests and evaluations

Reference Files

• references/nuget-packaging.md — Complete NuGet .csproj configuration, server.json for MCP, NuGet.org push, testing with dnx, version management. Load when: publishing a stdio server to NuGet.
• references/docker-azure.md — Production Dockerfile patterns, ACR setup, Azure Container Apps full configuration, App Service with Key Vault, secrets management. Load when: deploying an HTTP server to Docker or Azure.
• references/mcp-registry.md — mcp-publisher CLI installation, server.json schema, namespace conventions (GitHub vs DNS auth), CI/CD automation. Load when: publishing to the official MCP Registry.

More Info

• NuGet publishing — NuGet.org publishing guide
• Azure Container Apps — Serverless container hosting
• MCP Registry — Official MCP server registry