Add AIJsonSchemaCreateOptions.IncludeParameter filter

src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonSchemaCreateOptions.cs

@@ -2,7 +2,9 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Reflection;
 using System.Text.Json.Nodes;
+using System.Threading;
 
 #pragma warning disable S1067 // Expressions should not be too complex
 
@@ -23,6 +25,18 @@ public sealed class AIJsonSchemaCreateOptions : IEquatable<AIJsonSchemaCreateOpt
     /// </summary>
     public Func<AIJsonSchemaCreateContext, JsonNode, JsonNode>? TransformSchemaNode { get; init; }
 
+    /// <summary>
+    /// Gets a callback that is invoked for every parameter in the <see cref="MethodBase"/> provided to
+    /// <see cref="AIJsonUtilities.CreateFunctionJsonSchema"/> in order to determine whether it should
+    /// be included in the generated schema.
+    /// </summary>
+    /// <remarks>
+    /// By default, when <see cref="IncludeParameter"/> is <see langword="null"/>, all parameters other
+    /// than those of type <see cref="CancellationToken"/> are included in the generated schema.
+    /// The delegate is not invoked for <see cref="CancellationToken"/> parameters.
+    /// </remarks>
+    public Func<ParameterInfo, bool>? IncludeParameter { get; init; }
+
     /// <summary>
     /// Gets a value indicating whether to include the type keyword in inferred schemas for .NET enums.
     /// </summary>
@@ -44,19 +58,24 @@ public sealed class AIJsonSchemaCreateOptions : IEquatable<AIJsonSchemaCreateOpt
     public bool RequireAllProperties { get; init; } = true;
 
     /// <inheritdoc/>
-    public bool Equals(AIJsonSchemaCreateOptions? other)
-    {
-        return other is not null &&
-            TransformSchemaNode == other.TransformSchemaNode &&
-            IncludeTypeInEnumSchemas == other.IncludeTypeInEnumSchemas &&
-            DisallowAdditionalProperties == other.DisallowAdditionalProperties &&
-            IncludeSchemaKeyword == other.IncludeSchemaKeyword &&
-            RequireAllProperties == other.RequireAllProperties;
-    }
+    public bool Equals(AIJsonSchemaCreateOptions? other) =>
+        other is not null &&
+        TransformSchemaNode == other.TransformSchemaNode &&
+        IncludeParameter == other.IncludeParameter &&
+        IncludeTypeInEnumSchemas == other.IncludeTypeInEnumSchemas &&
+        DisallowAdditionalProperties == other.DisallowAdditionalProperties &&
+        IncludeSchemaKeyword == other.IncludeSchemaKeyword &&
+        RequireAllProperties == other.RequireAllProperties;
 
     /// <inheritdoc />
     public override bool Equals(object? obj) => obj is AIJsonSchemaCreateOptions other && Equals(other);
 
     /// <inheritdoc />
-    public override int GetHashCode() => (TransformSchemaNode, IncludeTypeInEnumSchemas, DisallowAdditionalProperties, IncludeSchemaKeyword, RequireAllProperties).GetHashCode();
+    public override int GetHashCode() =>
+        (TransformSchemaNode,
+         IncludeParameter,
+         IncludeTypeInEnumSchemas,
+         DisallowAdditionalProperties,
+         IncludeSchemaKeyword,
+         RequireAllProperties).GetHashCode();
 }

src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Schema.cs

@@ -87,6 +87,14 @@ public static JsonElement CreateFunctionJsonSchema(
                 continue;
             }
 
+            if (inferenceOptions.IncludeParameter is { } includeParameter &&
+                !includeParameter(parameter))
+            {
+                // Skip parameters that should not be included in the schema.
+                // By default, all parameters are included.
+                continue;
+            }
+
             JsonNode parameterSchema = CreateJsonSchemaCore(
                 type: parameter.ParameterType,
                 parameterName: parameter.Name,

test/Libraries/Microsoft.Extensions.AI.Abstractions.Tests/Utilities/AIJsonUtilitiesTests.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Linq;
 using System.Reflection;
@@ -10,6 +11,7 @@
 using System.Text.Json.Nodes;
 using System.Text.Json.Serialization;
 using System.Text.Json.Serialization.Metadata;
+using System.Threading;
 using Microsoft.Extensions.AI.JsonSchemaExporter;
 using Xunit;
 
@@ -86,6 +88,12 @@ public static void AIJsonSchemaCreateOptions_UsesStructuralEquality()
                     property.SetValue(options2, transformer);
                     break;
 
+                case null when property.PropertyType == typeof(Func<ParameterInfo, bool>):
+                    Func<ParameterInfo, bool> includeParameter = static (parameter) => true;
+                    property.SetValue(options1, includeParameter);
+                    property.SetValue(options2, includeParameter);
+                    break;
+
                 default:
                     Assert.Fail($"Unexpected property type: {property.PropertyType}");
                     break;
@@ -443,6 +451,31 @@ public static void HashData_Idempotent()
         }
     }
 
+    [Fact]
+    public static void CreateFunctionJsonSchema_InvokesIncludeParameterCallbackForEveryParameter()
+    {
+        Delegate method = (int first, string second, bool third, CancellationToken fourth, DateTime fifth) => { };
+
+        List<string?> names = [];
+        JsonElement schema = AIJsonUtilities.CreateFunctionJsonSchema(method.Method, inferenceOptions: new()
+        {
+            IncludeParameter = p =>
+            {
+                names.Add(p.Name);
+                return p.Name is "first" or "fifth";
+            }
+        });
+
+        Assert.Equal(["first", "second", "third", "fifth"], names);
+
+        string schemaString = schema.ToString();
+        Assert.Contains("first", schemaString);
+        Assert.DoesNotContain("second", schemaString);
+        Assert.DoesNotContain("third", schemaString);
+        Assert.DoesNotContain("fourth", schemaString);
+        Assert.Contains("fifth", schemaString);
+    }
+
     private class DerivedAIContent : AIContent
     {
         public int DerivedValue { get; set; }

test/Libraries/Microsoft.Extensions.AI.Tests/Functions/AIFunctionFactoryTest.cs

@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Reflection;
+using System.Text.Json;
 using System.Threading;
 using System.Threading.Tasks;
 using Xunit;
@@ -172,4 +173,29 @@ public void AIFunctionFactoryOptions_DefaultValues()
         Assert.Null(options.SerializerOptions);
         Assert.Null(options.JsonSchemaCreateOptions);
     }
+
+    [Fact]
+    public async Task AIFunctionFactoryOptions_SupportsSkippingParameters()
+    {
+        AIFunction func = AIFunctionFactory.Create(
+            (string firstParameter, int secondParameter) => firstParameter + secondParameter,
+            new()
+            {
+                JsonSchemaCreateOptions = new()
+                {
+                    IncludeParameter = p => p.Name != "firstParameter",
+                }
+            });
+
+        Assert.DoesNotContain("firstParameter", func.JsonSchema.ToString());
+        Assert.Contains("secondParameter", func.JsonSchema.ToString());
+
+        JsonElement? result = (JsonElement?)await func.InvokeAsync(new Dictionary<string, object?>
+        {
+            ["firstParameter"] = "test",
+            ["secondParameter"] = 42
+        });
+        Assert.NotNull(result);
+        Assert.Contains("test42", result.ToString());
+    }
 }