[MCP Server]: Non -SDK-style projects not supported

[madskristensen]

Issue Type

Bug

MCP Server Package Version

No response

.NET Version

.NET Framework 4.8

Environment

• Visual Studio
• VS Code
• GitHub Copilot Coding Agent
• CLI
• Other (please specify below)

If "Other", please specify

No response

Prompt or Input

Install NuGet package xyz

Expected Response

The package being installed

Actual Response

The response is that the .csproj file is being edited with invalid XML leading the project to being unloaded in VS. In injects '\ between two package references. The only way to fix it is to open the .csproj in an external editor and fix the syntax error. Then manual install the nuget package before letting Copilot to continue.

Additional Context or Description

I don't know if this is the NuGet MCP server or Copilot in general that causes this issue, but it seem that if NuGet MCP supported non-SDK-style .NET Full Framework projects then it would be fixed.

[jebriede]

In my attempts to repro, Copilot, using Claude Sonnet 4.5, tried to add the package using dotnet add ConsoleApp1\ConsoleApp1.csproj package Newtonsoft.Json but failed. It seems that Copilot will try to edit the csproj file directly or use the CLI to add the package but it won't succeed on non-SDK style projects.

When I switched the model to GPT-4.1, it tried to use a variety of CLI options, all of which failed.

When I switched the model to GPT-5.2, it tried a few CLI options and then gave instructions on how to add the package through the NuGet Package Manager in VS or on the command line.

Overall, the experience of installing a NuGet package to a non-SDK style project using Copilot seems to result in a failed attempt. I'm marking this as a Feature request so we can consider adding a package install operation to the MCP Server or defer to GitHub Copilot.