Radzen.mcp with Visual Studio (Insiders)

rzhv · January 30, 2026, 5:21am

Hi,

Thought I’d test this out. I was able to install successfully via
dotnet tool install --global Radzen.Mcp

Running the `radzen.mcp` command gave me an error as it was trying to read my current project’s appsettings.json.

radzen.mcp
radzen.mcp : Unhandled exception. System.IO.InvalidDataException: Failed to load configuration from file 'C:\ProjectFolder\appsettings.json'.
At line:1 char:1
+ radzen.mcp
+ ~~~~~~~~~~
    + CategoryInfo          : NotSpecified: (Unhandled excep...settings.json'.:String) [], RemoteException
    + FullyQualifiedErrorId : NativeCommandError
 
 ---> System.FormatException: Could not parse the JSON file.
 ---> System.Text.Json.JsonReaderException: The input does not contain any JSON tokens. Expected the input to start with a valid JSON token, when isFinalBlock is true. LineNumber: 0 | BytePositionInLine: 0.
   at System.Text.Json.ThrowHelper.ThrowJsonReaderException(Utf8JsonReader& json, ExceptionResource resource, Byte nextByte, ReadOnlySpan`1 bytes)
   at System.Text.Json.Utf8JsonReader.Read()
   at System.Text.Json.JsonDocument.Parse(ReadOnlySpan`1 utf8JsonSpan, JsonReaderOptions readerOptions, MetadataDb& database, StackRowStack& stack)
   at System.Text.Json.JsonDocument.Parse(ReadOnlyMemory`1 utf8Json, JsonReaderOptions readerOptions, Byte[] extraRentedArrayPoolBytes, PooledByteBufferWriter extraPooledByteBufferWriter)
   at System.Text.Json.JsonDocument.Parse(ReadOnlyMemory`1 json, JsonDocumentOptions options)
   at System.Text.Json.JsonDocument.Parse(String json, JsonDocumentOptions options)
   at Microsoft.Extensions.Configuration.Json.JsonConfigurationFileParser.ParseStream(Stream input)
   at Microsoft.Extensions.Configuration.Json.JsonConfigurationFileParser.Parse(Stream input)
   at Microsoft.Extensions.Configuration.Json.JsonConfigurationProvider.Load(Stream stream)
   --- End of inner exception stack trace ---
   at Microsoft.Extensions.Configuration.Json.JsonConfigurationProvider.Load(Stream stream)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load(Boolean reload)
   --- End of inner exception stack trace ---
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.HandleException(ExceptionDispatchInfo info)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load(Boolean reload)
   at Microsoft.Extensions.Configuration.FileConfigurationProvider.Load()
   at Microsoft.Extensions.Configuration.ConfigurationManager.AddSource(IConfigurationSource source)
   at Microsoft.Extensions.Configuration.ConfigurationManager.ConfigurationSources.Add(IConfigurationSource source)
   at Microsoft.Extensions.Configuration.ConfigurationManager.Microsoft.Extensions.Configuration.IConfigurationBuilder.Add(IConfigurationSource source)
   at Microsoft.Extensions.Configuration.ConfigurationExtensions.Add[TSource](IConfigurationBuilder builder, Action`1 configureSource)
   at Microsoft.Extensions.Configuration.JsonConfigurationExtensions.AddJsonFile(IConfigurationBuilder builder, Action`1 configureSource)
   at Microsoft.Extensions.Configuration.JsonConfigurationExtensions.AddJsonFile(IConfigurationBuilder builder, IFileProvider provider, String path, Boolean optional, Boolean reloadOnChange)
   at Microsoft.Extensions.Configuration.JsonConfigurationExtensions.AddJsonFile(IConfigurationBuilder builder, String path, Boolean optional, Boolean reloadOnChange)
   at Microsoft.Extensions.Hosting.HostingHostBuilderExtensions.ApplyDefaultAppConfiguration(HostBuilderContext hostingContext, IConfigurationBuilder appConfigBuilder, String[] args)
   at Microsoft.Extensions.Hosting.HostApplicationBuilder..ctor(HostApplicationBuilderSettings settings)
   at Microsoft.Extensions.Hosting.HostApplicationBuilder..ctor(String[] args)
   at Microsoft.Extensions.Hosting.Host.CreateApplicationBuilder(String[] args)
   at Program.<Main>$(String[] args) in /home/runner/work/radzen-mcp/radzen-mcp/Radzen.Mcp/Program.cs:line 26
   at Program.<Main>(String[] args)
PM>

I ran it from an empty directory and got a server process running - which I closed afterwards as well.

 rmcp  radzen.mcp
info: ModelContextProtocol.Server.StdioServerTransport[857250842]
Server (stream) (Radzen.Mcp) transport reading messages.
info: Microsoft.Hosting.Lifetime[0]
Application started. Press Ctrl+C to shut down.
info: Microsoft.Hosting.Lifetime[0]
Hosting environment: Production
info: Microsoft.Hosting.Lifetime[0]
Content root path: C:\Users\me\rmcp
info: ModelContextProtocol.Server.StdioServerTransport[1221292038]
Server (stream) (Radzen.Mcp) transport completed reading messages.
info: Microsoft.Hosting.Lifetime[0]
Application is shutting down...
info: ModelContextProtocol.Server.McpServer[2081236114]
Server (Radzen.Mcp 0.0.3.0) shutting down.
info: ModelContextProtocol.Server.McpServer[613617602]
Server (Radzen.Mcp 0.0.3.0) shut down.
info: ModelContextProtocol.Server.StdioServerTransport[1375634372]
Server (stream) (Radzen.Mcp) shutting down.
info: ModelContextProtocol.Server.StdioServerTransport[1256455528]
Server (stream) (Radzen.Mcp) shut down.

I added the .mcp.json to VS 2026 Insiders in my solution. I restarted VS..

I clicked the spanners button in CoPilot tab - I clicked to check Radzen MCP and get a red X.
If I click the “…“ I can see the mcp.json file - if I hit configure. I see the failed message.

Click Restart shows starting for a few seconds, then Failed.

I tried hitting Restart with it running in the other Terminal prompt. Same error..

So, not sure what else to do?

korchev · January 30, 2026, 2:10pm

Hi @rzhv,

This is a very strange error indeed. It seems that there is an empty appsettings.json somewhere which gets picked up when VS tries to start the MCP server. Unfortunately we can't tell more.

rzhv · January 31, 2026, 7:21am

It’s not empty, it picks the appsettings for the current project for the folder I was in via the Visual Studio command prompt. I guess it’s missing settings it wants to see??
but like I said, if I run MCP via command prompt in an empty folder, it starts OK but VS still doesn’t see it and gives the Failed message.
Should this be run on its own and VS should find it?

korchev · January 31, 2026, 7:59am

The IDE is supposed to start the MCP server process. Still not sure why you are seeing this exception. Is you appsettings.json file valid? What happens if you try with a new empty application?

rzhv · January 31, 2026, 8:44am

I added the .mcp.json file to another project it worked no issue..
I’ll see if I can find an error somewhere for the other one..

rzhv · February 1, 2026, 3:22am

ok, good news.. On restart today, the original solution that kept blocking the Radzen.mcp has loaded it successfully. Who knows what went wrong.. thanks for your help.

rzhv · February 10, 2026, 12:50pm

for some reason today, I’ve had lots of “Activation of the server ‘radzen.mcp’ failed.”

Seems to fix for a while after VS restart..

rzhv · February 22, 2026, 9:18am

anyone else get this? It’s an almost daily occurrence for me..