Create a project template for an MCP server

[joelverhagen]

This addresses #6518.

The conventions we're pushing for on NuGet are:

1. PackAsTool
2. McpServer package type (in addition to the default DotnetTool)
3. Embed server.json (docs)

Commands I use to test locally

# build + install
.\build.cmd -pack -projects .\src\ProjectTemplates\Microsoft.Extensions.AI.Templates\Microsoft.Extensions.AI.Templates.csproj
dotnet new uninstall Microsoft.Extensions.AI.Templates
dotnet new install Microsoft.Extensions.AI.Templates::9.7.0-dev --add-source Q:\src\dotnet-extensions\artifacts\packages\Debug\Shipping

# clear test directory and run template
gci Q:\trash\2025-06-25\template-try-2\* -Recurse | Remove-Item -Force -Recurse -Confirm:$false
dotnet new mcpserver
dotnet build
dotnet pack

TODO (for me, before merge):

• Enhance template README
• Add icon
• Add tests
  • Skipped the execution test for now since it requires .NET 10 SDK, filed Add execution tests to the MCP server template #6563.

TODO (for me, after merge):

• Track server.json versioning (Document server.json modelcontextprotocol/registry#90 (comment))
• Track server.json embedding convention (Document convention: server.json presence in package artifact modelcontextprotocol/registry#137 (comment)).
• Preview 7 timeframe: switch the template to self-contained packages per Improve the MCP server template to produce self-contained packages #6560
• Update aka.ms/nuget/mcp/guide and aka.ms/nuget/mcp/guide/configuring-inputs

Open question (for repo owners/reviewers):

• How do we ship this template?
  • Answer: as part of the existing AI templates with the chat template
• How can this template be marked as "preview"?
  • Answer: it will be part of the Preview 6 release and have the associated marker
• How do we keep the Hosting and MCP SDK dependency fresh?
  • We will assess during Preview 7 timeframe (follow-up PR?)

Screenshots:

VS IDE - light mode:

VS IDE - dark mode:

Microsoft Reviewers: Open in CodeFlow

[timheuer]

I had created my own as I've been iterating on a few things https://github.com/timheuer/dotnet-mcp-server -- I think we should organize like the samples (Tools, etc.) rather than everything in Program.cs. Mine has some options to use http transport as well, arguable if that's needed in a v1, but easy to do.

[joelverhagen]

I had created my own as I've been iterating on a few things https://github.com/timheuer/dotnet-mcp-server -- I think we should organize like the samples (Tools, etc.) rather than everything in Program.cs. Mine has some options to use http transport as well, arguable if that's needed in a v1, but easy to do.

I like the Program.cs since it's small and easy to wrap your head around. You can see without much code the whole thing work and have an idea of where to plug in your custom MCP logic. I agree mature organization (not to mention having resources, and prompts in addition to tools) are a good thing to cover somewhere.

Is there prior art for a "minimal" vs. "organized" template variants? Maybe we can call this one mcpserver-minimal or something and add a bigger one later?

I am trying to see if there's a lean thing we can release soon, and then layer improvements on after that. Preview 6 has everything we need for E2E (with dotnet tool exec) so I wanted something to ship at the same time or soon after Preview 6. Preview 7 or OOB could have more.

What do you think?

[timheuer]

Maybe we can call this one mcpserver-minimal or something and add a bigger one later?

No, see my previous comment about templates -- we really should have one MCP template...if it doesn't match our samples, we should question which one is better and why. Templates should be our best practices as we codify them.

[joelverhagen]

@timheuer, @MackinnonBuck, @jeffhandley, @stephentoub - I believe this is ready for review!

[timheuer]

made one suggestion to Joel in chat else looks good to me.

[MackinnonBuck]

Looks great!