feat: Add support for Model Context Protocol

src/Cellm.Models/Behaviors/ToolBehavior.cs

@@ -1,22 +1,73 @@
-using Cellm.Models.Providers;
+using System.Runtime.CompilerServices;
+using Cellm.Models.Providers;
+using Cellm.Tools.ModelContextProtocol;
 using MediatR;
 using Microsoft.Extensions.AI;
 using Microsoft.Extensions.Options;
+using ModelContextProtocol.Client;
 
 namespace Cellm.Models.Tools;
 
-internal class ToolBehavior<TRequest, TResponse>(IOptionsMonitor<ProviderConfiguration> providerConfiguration, IEnumerable<AIFunction> functions)
+internal class ToolBehavior<TRequest, TResponse>(
+    IOptionsMonitor<ProviderConfiguration> providerConfiguration,
+    IOptionsMonitor<ModelContextProtocolConfiguration> modelContextProtocolConfiguration,
+    IEnumerable<AIFunction> functions)
     : IPipelineBehavior<TRequest, TResponse> where TRequest : IModelRequest<TResponse>
 {
     public async Task<TResponse> Handle(TRequest request, RequestHandlerDelegate<TResponse> next, CancellationToken cancellationToken)
     {
         if (providerConfiguration.CurrentValue.EnableTools.Any(t => t.Value))
         {
-            request.Prompt.Options.Tools = functions
-                .Where(f => providerConfiguration.CurrentValue.EnableTools[f.Name])
-                .ToList<AITool>();
+            request.Prompt.Options.Tools = GetNativeTools();
+        }
+
+        if (providerConfiguration.CurrentValue.EnableModelContextProtocolServers.Any(t => t.Value))
+        {
+            request.Prompt.Options.Tools ??= [];
+
+            await foreach (var tool in GetModelContextProtocolTools(cancellationToken))
+            {
+                request.Prompt.Options.Tools.Add(tool);
+            }
         }
 
         return await next();
     }
+
+    private List<AITool> GetNativeTools()
+    {
+        return functions
+                .Where(f => providerConfiguration.CurrentValue.EnableTools[f.Name])
+                .ToList<AITool>();
+    }
+
+    // TODO:
+    //  - Cache capabilities on a per-server basis.
+    //  - Query servers in parallel.
+    //
+    //  Note: We cannot get list of tools only on startup because user can add/delete/enable/disable servers. But
+    //        with this solution we query servers for capabilities on every model call which is hardly ideal.
+    //        We need to cache on a per-server basis so servers added at runtime will be queried
+    private async IAsyncEnumerable<AITool> GetModelContextProtocolTools([EnumeratorCancellation] CancellationToken cancellationToken)
+    {
+        foreach (var server in modelContextProtocolConfiguration.CurrentValue.Servers)
+        {
+            if (!providerConfiguration.CurrentValue.EnableModelContextProtocolServers.TryGetValue(server.Name, out var isEnabled) || !isEnabled)
+            {
+                continue;
+            }
+
+            var client = await McpClientFactory.CreateAsync(server, cancellationToken: cancellationToken);
+
+            if (client is null)
+            {
+                continue;
+            }
+
+            foreach (var tool in await client.ListToolsAsync(cancellationToken: cancellationToken))
+            {
+                yield return tool;
+            }
+        }
+    }
 }

src/Cellm.Models/Providers/ProviderConfiguration.cs

@@ -1,4 +1,6 @@
-namespace Cellm.Models.Providers;
+using ModelContextProtocol;
+
+namespace Cellm.Models.Providers;
 
 public class ProviderConfiguration : IProviderConfiguration
 {
@@ -12,6 +14,10 @@ public class ProviderConfiguration : IProviderConfiguration
 
     public Dictionary<string, bool> EnableTools { get; init; } = [];
 
+    public Dictionary<string, bool> EnableModelContextProtocolServers { get; init; } = [];
+
+    public Dictionary<string, McpServerConfig> ModelContextProtocolServers { get; init; } = [];
+
     public bool EnableCache { get; init; } = true;
 
     public int CacheTimeoutInSeconds { get; init; } = 3600;

src/Cellm/AddIn/ExcelRibbon.cs

@@ -231,12 +231,12 @@ public bool OnGetCachePressed(IRibbonControl control)
 
     public void OnFileSearchToggled(IRibbonControl control, bool pressed)
     {
-        SetValue("ProviderConfiguration:EnableTools:GlobRequest", pressed.ToString());
+        SetValue("ProviderConfiguration:EnableTools:FileSearchRequest", pressed.ToString());
     }
 
     public bool OnGetFileSearchPressed(IRibbonControl control)
     {
-        var value = GetValue("ProviderConfiguration:EnableTools:GlobRequest");
+        var value = GetValue("ProviderConfiguration:EnableTools:FileSearchRequest");
         return bool.Parse(value);
     }
 

src/Cellm/Cellm.csproj

@@ -46,6 +46,7 @@
     <PackageReference Include="Microsoft.Extensions.Logging.Debug" Version="9.0.3" />
     <PackageReference Include="Microsoft.Extensions.Options" Version="9.0.3" />
     <PackageReference Include="Microsoft.Extensions.Options.ConfigurationExtensions" Version="9.0.3" />
+    <PackageReference Include="ModelContextProtocol" Version="0.1.0-preview.6" />
     <PackageReference Include="PdfPig" Version="0.1.10" />
     <PackageReference Include="Sentry.Extensions.Logging" Version="5.5.0" />
     <PackageReference Include="Sentry.Profiling" Version="5.5.0" />

src/Cellm/Services/ServiceLocator.cs

@@ -16,6 +16,7 @@
 using Cellm.Services.Configuration;
 using Cellm.Tools;
 using Cellm.Tools.FileReader;
+using Cellm.Tools.ModelContextProtocol;
 using ExcelDna.Integration;
 using Microsoft.Extensions.AI;
 using Microsoft.Extensions.Caching.Memory;
@@ -48,8 +49,9 @@ private static IServiceCollection ConfigureServices(IServiceCollection services)
             .Build();
 
         services
-            .Configure<CellmConfiguration>(configuration.GetRequiredSection(nameof(CellmConfiguration)))
             .Configure<ProviderConfiguration>(configuration.GetRequiredSection(nameof(ProviderConfiguration)))
+            .Configure<ModelContextProtocolConfiguration>(configuration.GetRequiredSection(nameof(ModelContextProtocolConfiguration)))
+            .Configure<CellmConfiguration>(configuration.GetRequiredSection(nameof(CellmConfiguration)))
             .Configure<AnthropicConfiguration>(configuration.GetRequiredSection(nameof(AnthropicConfiguration)))
             .Configure<DeepSeekConfiguration>(configuration.GetRequiredSection(nameof(DeepSeekConfiguration)))
             .Configure<LlamafileConfiguration>(configuration.GetRequiredSection(nameof(LlamafileConfiguration)))
@@ -129,10 +131,12 @@ private static IServiceCollection ConfigureServices(IServiceCollection services)
             .AddSingleton<FileReaderFactory>()
             .AddSingleton<IFileReader, PdfReader>()
             .AddSingleton<IFileReader, TextReader>()
-            .AddSingleton<Functions>()
+            .AddSingleton<NativeTools>()
             .AddTools(
-                serviceProvider => AIFunctionFactory.Create(serviceProvider.GetRequiredService<Functions>().GlobRequest),
-                serviceProvider => AIFunctionFactory.Create(serviceProvider.GetRequiredService<Functions>().FileReaderRequest));
+                serviceProvider => AIFunctionFactory.Create(serviceProvider.GetRequiredService<NativeTools>().FileSearchRequest),
+                serviceProvider => AIFunctionFactory.Create(serviceProvider.GetRequiredService<NativeTools>().FileReaderRequest));
+
+        // Workarounds
 
         // https://github.com/openai/openai-dotnet/issues/297
         var metricsFilterDescriptor = services.FirstOrDefault(descriptor =>

src/Cellm/Tools/FileSearch/FileSearchRequest.cs

@@ -0,0 +1,5 @@
+using MediatR;
+
+namespace Cellm.Tools.FileSearch;
+
+internal record FileSearchRequest(string RootPath, List<string> IncludePatterns, List<string>? ExcludePatterns) : IRequest<FileSearchResponse>;

src/Cellm/Tools/Glob/GlobRequestHandler.cs → src/Cellm/Tools/FileSearch/FileSearchRequestHandler.cs

@@ -1,17 +1,17 @@
 using MediatR;
 using Microsoft.Extensions.FileSystemGlobbing;
 
-namespace Cellm.Tools.Glob;
+namespace Cellm.Tools.FileSearch;
 
-internal class GlobRequestHandler : IRequestHandler<GlobRequest, GlobResponse>
+internal class FileSearchRequestHandler : IRequestHandler<FileSearchRequest, FileSearchResponse>
 {
-    public Task<GlobResponse> Handle(GlobRequest request, CancellationToken cancellationToken)
+    public Task<FileSearchResponse> Handle(FileSearchRequest request, CancellationToken cancellationToken)
     {
         var matcher = new Matcher();
         matcher.AddIncludePatterns(request.IncludePatterns);
         matcher.AddExcludePatterns(request.ExcludePatterns ?? []);
         var fileNames = matcher.GetResultsInFullPath(request.RootPath);
 
-        return Task.FromResult(new GlobResponse(fileNames.ToList()));
+        return Task.FromResult(new FileSearchResponse(fileNames.ToList()));
     }
 }

src/Cellm/Tools/FileSearch/FileSearchResponse.cs

@@ -0,0 +1,3 @@
+namespace Cellm.Tools.FileSearch;
+
+internal record FileSearchResponse(List<string> FilePaths);

src/Cellm/Tools/ModelContextProtocol/ModelContextProtocolConfiguration.cs

@@ -0,0 +1,8 @@
+using ModelContextProtocol;
+
+namespace Cellm.Tools.ModelContextProtocol;
+
+internal class ModelContextProtocolConfiguration
+{
+    public List<McpServerConfig> Servers { get; init; } = [];
+}

src/Cellm/Tools/Functions.cs → src/Cellm/Tools/NativeTools.cs

@@ -1,6 +1,6 @@
 using System.ComponentModel;
 using Cellm.Tools.FileReader;
-using Cellm.Tools.Glob;
+using Cellm.Tools.FileSearch;
 using MediatR;
 
 namespace Cellm.Tools;
@@ -9,17 +9,17 @@ namespace Cellm.Tools;
 /// Provides an adapter between MediatR and Microsoft.Extensions.AI by wrapping 
 /// request handlers in function definitions suitable for the AIFunctionFactory.
 /// </summary>
-internal class Functions(ISender sender)
+internal class NativeTools(ISender sender)
 {
     [Description("Uses glob patterns to search for files on the user's disk and returns matching file paths.")]
     [return: Description($"The list of file paths that matches {nameof(includePatterns)} and do not match {nameof(excludePatterns)}")]
-    public async Task<GlobResponse> GlobRequest(
+    public async Task<FileSearchResponse> FileSearchRequest(
     [Description("The root directory to start the glob search from")] string rootPath,
     [Description("The list of glob patterns whose matches will be included in the result")] List<string> includePatterns,
     [Description("An optional list of glob patterns whose matches will be excluded from the result")] List<string>? excludePatterns,
     CancellationToken cancellationToken)
     {
-        return await sender.Send(new GlobRequest(rootPath, includePatterns, excludePatterns), cancellationToken);
+        return await sender.Send(new FileSearchRequest(rootPath, includePatterns, excludePatterns), cancellationToken);
     }
 
     [Description("Reads a file and returns its content as plain text.")]

src/Cellm/appsettings.json

@@ -74,10 +74,27 @@
         "CacheTimeoutInSeconds": 3600,
         "EnableCache": true,
         "EnableTools": {
-            "GlobRequest": false,
+            "FileSearchRequest": false,
             "FileReaderRequest": false
+        },
+        "EnableModelContextProtocolServers": {
+            "Everything": true
         }
     },
+    "ModelContextProtocolConfiguration": {
+        "Servers": [
+            {
+                "Id": "everything",
+                "Name": "Everything",
+                "TransportType": "stdio",
+                "Location": "path",
+                "TransportOptions": {
+                    "command": "npx",
+                    "arguments": "-y @modelcontextprotocol/server-everything"
+                }
+            }
+        ]
+    },
     "ResilienceConfiguration": {
         "RateLimiterConfiguration": {
             "QueueLimit": 1048576,

src/Cellm/packages.lock.json

@@ -232,6 +232,18 @@
           "Microsoft.Extensions.Primitives": "9.0.3"
         }
       },
+      "ModelContextProtocol": {
+        "type": "Direct",
+        "requested": "[0.1.0-preview.6, )",
+        "resolved": "0.1.0-preview.6",
+        "contentHash": "gq6mQYvtaGC8lhWHBS4X5Ck53+HNWZPiqO7hOEOFRRLO30OlrXX9I+Uz9ShvfTAnjwvugV3TfMH2UbpBXusBtw==",
+        "dependencies": {
+          "Microsoft.Extensions.AI.Abstractions": "9.3.0-preview.1.25161.3",
+          "Microsoft.Extensions.Hosting.Abstractions": "9.0.0",
+          "Microsoft.Extensions.Logging.Abstractions": "9.0.0",
+          "System.Net.ServerSentEvents": "10.0.0-preview.2.25163.2"
+        }
+      },
       "PdfPig": {
         "type": "Direct",
         "requested": "[0.1.10, )",
@@ -566,6 +578,11 @@
         "resolved": "9.0.3",
         "contentHash": "QH23aqk1Cr1oSP9zEbjsJ60M7nbYOSEQLXszzxK12VXjEOXasnI8pnF7WeME66+z8OoecHfIL8iGxCRxjFQXFQ=="
       },
+      "System.Net.ServerSentEvents": {
+        "type": "Transitive",
+        "resolved": "10.0.0-preview.2.25163.2",
+        "contentHash": "XHyvtQSgco0Sv0kz9yNBv93k3QOoAVzIVd5XbQoTqjV9sqkzWHsToNknyxtNjcXQwb+O9TfzSlNobsBWwnKD3Q=="
+      },
       "System.Text.Json": {
         "type": "Transitive",
         "resolved": "9.0.3",