.Net: Add OpenApi parameter description to its schema

dotnet/src/Functions/Functions.OpenApi/OpenApiKernelPluginFactory.cs

@@ -8,6 +8,8 @@
 using System.Linq;
 using System.Net.Http;
 using System.Text;
+using System.Text.Json;
+using System.Text.Json.Nodes;
 using System.Text.RegularExpressions;
 using System.Threading;
 using System.Threading.Tasks;
@@ -295,7 +297,7 @@ async Task<RestApiOperationResponse> ExecuteAsync(Kernel kernel, KernelFunction
                 DefaultValue = p.DefaultValue ?? string.Empty,
                 IsRequired = p.IsRequired,
                 ParameterType = ConvertParameterDataType(p),
-                Schema = p.Schema ?? (p.Type is null ? null : KernelJsonSchema.Parse($$"""{"type":"{{p.Type}}"}""")),
+                Schema = GetSchema(p)
             })
             .ToList();
 
@@ -329,6 +331,28 @@ async Task<RestApiOperationResponse> ExecuteAsync(Kernel kernel, KernelFunction
             });
     }
 
+    private static KernelJsonSchema? GetSchema(RestApiParameter p)
+    {
+        // Add description to the schema.
+        if (p.Schema is not null && !string.IsNullOrEmpty(p.Description))
+        {
+            const string DescriptionPropertyName = "description";
+
+            // If the schema does not already have a description, add it.
+            if (!p.Schema.RootElement.TryGetProperty(DescriptionPropertyName, out var _))
+            {
+                var originalSchema = JsonSerializer.Serialize(p.Schema.RootElement);
+                if (JsonNode.Parse(originalSchema) is JsonObject obj)
+                {
+                    obj.Add(DescriptionPropertyName, p.Description);
+                    p.Schema = KernelJsonSchema.Parse(obj.ToString());
+                }
+            }
+        }
+
+        return p.Schema ?? (p.Type is null ? null : KernelJsonSchema.Parse($$"""{"type":"{{p.Type}}"}"""));
+    }
+
     #region private
 
     /// <summary>The metadata property bag key to use when storing the method of an operation.</summary>

dotnet/src/Functions/Functions.UnitTests/OpenApi/OpenApiKernelPluginFactoryTests.cs

@@ -715,6 +715,27 @@ public async Task ItShouldCreateFunctionWithMultipartFormDataAsync()
         Assert.False(plugin.TryGetFunction("createItem", out var _));
     }
 
+    [Fact]
+    public async Task ItCanAddPropertyDescriptionToSchemaAsync()
+    {
+        // Act
+        var plugin = await OpenApiKernelPluginFactory.CreateFromOpenApiAsync("fakePlugin", this._openApiDocument, this._executionParameters);
+
+        // Assert
+        var setSecretFunction = plugin["SetSecret"];
+        Assert.NotNull(setSecretFunction);
+
+        var functionView = setSecretFunction.Metadata;
+        Assert.NotNull(functionView);
+
+        // Check if description is added to the parameter schema
+        var secretNameParameter = functionView.Parameters.First(p => p.Name == "secret_name");
+        Assert.Equal("The name of the secret", secretNameParameter.Description);
+
+        Assert.True(secretNameParameter.Schema!.RootElement.TryGetProperty("description", out var description));
+        Assert.Equal("The name of the secret", description.GetString());
+    }
+
     [Fact]
     public void Dispose()
     {

dotnet/src/Functions/Functions.UnitTests/OpenApi/TestPlugins/documentV2_0.json

@@ -83,6 +83,7 @@
             "in": "path",
             "name": "secret-name",
             "required": true,
+            "description": "The name of the secret",
             "type": "string"
           },
           {

dotnet/src/Functions/Functions.UnitTests/OpenApi/TestPlugins/documentV3_0.json

@@ -88,6 +88,7 @@
             "name": "secret-name",
             "in": "path",
             "required": true,
+            "description": "The name of the secret",
             "schema": {
               "type": "string"
             }

dotnet/src/Functions/Functions.UnitTests/OpenApi/TestPlugins/documentV3_1.yaml

@@ -57,6 +57,7 @@ paths:
         - name: secret-name
           in: path
           required: true
+          description: The name of the secret
           schema:
             type: string
         - name: api-version