Integrate Microsoft.Extensions.AI as a foundational building block (#94)

* Integrate Microsoft.Extensions.AI as a foundational building block

As with logging abstractions coming from M.E.Logging and DI abstractions coming from M.E.DependencyInjection, M.E.AI provides the relevant AI abstractions.

- Adds AsAIFunction and GetAIFunctionsAsync methods for getting functions for tools via a client.
- Uses AIFunctionFactory to implement McpServerBuilderExtensions.WithTools.
- Adds a RequestSamplingAsync overload that accepts ChatMessages/Options.
- Adds an AsSamplingChatClient method that provides an IChatClient usable on the server to request sampling of the client.
- Adds a CreateSamplingHandler method to enable an IChatClient to be easily used to satisfy sampling requests on the client.
- Deprecate McpDotNet.Extensions.AI.

* Address PR feedback

src/mcpdotnet/Protocol/Types/Content.cs

@@ -39,28 +39,4 @@ public class Content
     /// </summary>
     [JsonPropertyName("resource")]
     public ResourceContents? Resource { get; set; }
-
-    /// <summary>
-    /// Validates the content object. 
-    /// </summary>
-    /// <returns>Whether the type of tool content has the correct data fields provided.</returns>
-    public bool Validate()
-    {
-        if (Type == "text")
-        {
-            return !string.IsNullOrEmpty(Text);
-        }
-        else if (Type == "image")
-        {
-            return !string.IsNullOrEmpty(Data) && !string.IsNullOrEmpty(MimeType);
-        }
-        else if (Type == "resource")
-        {
-            return Resource != null;
-        }
-        else
-        {
-            return false;
-        }
-    }
 }

src/mcpdotnet/Protocol/Types/CreateMessageRequestParams.cs

@@ -21,7 +21,7 @@ public class CreateMessageRequestParams
     /// The maximum number of tokens to sample, as requested by the server. The client MAY choose to sample fewer tokens than requested.
     /// </summary>
     [System.Text.Json.Serialization.JsonPropertyName("maxTokens")]
-    public int MaxTokens { get; init; }
+    public int? MaxTokens { get; init; }
 
     /// <summary>
     /// Messages requested by the server to be included in the prompt.

src/mcpdotnet/Protocol/Types/JsonSchema.cs

@@ -10,7 +10,7 @@ public class JsonSchema
     /// The type of the schema, should be "object".
     /// </summary>
     [System.Text.Json.Serialization.JsonPropertyName("type")]
-    public string Type { get; set; } = string.Empty;
+    public string Type { get; set; } = "object";
 
     /// <summary>
     /// Map of property names to property definitions.

src/mcpdotnet/Protocol/Types/JsonSchemaProperty.cs

@@ -16,5 +16,5 @@ public class JsonSchemaProperty
     /// A human-readable description of the property.
     /// </summary>
     [System.Text.Json.Serialization.JsonPropertyName("description")]
-    public string? Description { get; set; }
+    public string? Description { get; set; } = string.Empty;
 }

src/mcpdotnet/Protocol/Types/Tool.cs

@@ -1,4 +1,6 @@
-namespace McpDotNet.Protocol.Types;
+using System.Text.Json.Serialization;
+
+namespace McpDotNet.Protocol.Types;
 
 /// <summary>
 /// Represents a tool that the server is capable of calling. Part of the ListToolsResponse.
@@ -9,18 +11,18 @@ public class Tool
     /// <summary>
     /// The name of the tool.
     /// </summary>
-    [System.Text.Json.Serialization.JsonPropertyName("name")]
+    [JsonPropertyName("name")]
     public string Name { get; set; } = string.Empty;
 
     /// <summary>
     /// A human-readable description of the tool.
     /// </summary>
-    [System.Text.Json.Serialization.JsonPropertyName("description")]
+    [JsonPropertyName("description")]
     public string? Description { get; set; }
 
     /// <summary>
     /// A JSON Schema object defining the expected parameters for the tool.
     /// </summary>
-    [System.Text.Json.Serialization.JsonPropertyName("inputSchema")]
+    [JsonPropertyName("inputSchema")]
     public JsonSchema? InputSchema { get; set; }
 }