Expose options for making schema generation conformant with the subset accepted by OpenAI.

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

@@ -16,15 +16,36 @@ public sealed class AIJsonSchemaCreateOptions
     /// <summary>
     /// Gets a value indicating whether to include the type keyword in inferred schemas for .NET enums.
     /// </summary>
-    public bool IncludeTypeInEnumSchemas { get; init; }
+    public bool IncludeTypeInEnumSchemas { get; init; } = true;
 
     /// <summary>
     /// Gets a value indicating whether to generate schemas with the additionalProperties set to false for .NET objects.
     /// </summary>
-    public bool DisallowAdditionalProperties { get; init; }
+    public bool DisallowAdditionalProperties { get; init; } = true;
 
     /// <summary>
     /// Gets a value indicating whether to include the $schema keyword in inferred schemas.
     /// </summary>
     public bool IncludeSchemaKeyword { get; init; }
+
+    /// <summary>
+    /// Gets a value indicating whether to mark all properties as required in the schema.
+    /// </summary>
+    public bool RequireAllProperties { get; init; } = true;
+
+    /// <summary>
+    /// Gets a value indicating whether to filter keywords that are disallowed by certain AI vendors.
+    /// </summary>
+    /// <remarks>
+    /// Filters a number of non-essential schema keywords that are not yet supported by some AI vendors.
+    /// These include:
+    /// <list type="bullet">
+    /// <item>The "minLength", "maxLength", "pattern", and "format" keywords.</item>
+    /// <item>The "minimum", "maximum", and "multipleOf" keywords.</item>
+    /// <item>The "patternProperties", "unevaluatedProperties", "propertyNames", "minProperties", and "maxProperties" keywords.</item>
+    /// <item>The "unevaluatedItems", "contains", "minContains", "maxContains", "minItems", "maxItems", and "uniqueItems" keywords.</item>
+    /// </list>
+    /// See also https://platform.openai.com/docs/guides/structured-outputs#some-type-specific-keywords-are-not-yet-supported.
+    /// </remarks>
+    public bool FilterDisallowedKeywords { get; init; } = true;
 }

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

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
 using System.ComponentModel;
 using System.Diagnostics;
 #if !NET9_0_OR_GREATER
@@ -30,7 +31,9 @@
     object? DefaultValue,
     bool IncludeSchemaUri,
     bool DisallowAdditionalProperties,
-    bool IncludeTypeInEnumSchemas);
+    bool IncludeTypeInEnumSchemas,
+    bool RequireAllProperties,
+    bool FilterDisallowedKeywords);
 
 namespace Microsoft.Extensions.AI;
 
@@ -52,6 +55,10 @@ public static partial class AIJsonUtilities
     /// <summary>Gets a JSON schema only accepting null values.</summary>
     private static readonly JsonElement _nullJsonSchema = ParseJsonElement("""{"type":"null"}"""u8);
 
+    // List of keywords used by JsonSchemaExporter but explicitly disallowed by some AI vendors.
+    // cf. https://platform.openai.com/docs/guides/structured-outputs#some-type-specific-keywords-are-not-yet-supported
+    private static readonly string[] _schemaKeywordsDisallowedByAIVendors = ["minLength", "maxLength", "pattern", "format"];
+
     /// <summary>
     /// Determines a JSON schema for the provided parameter metadata.
     /// </summary>
@@ -122,7 +129,9 @@ public static JsonElement CreateParameterJsonSchema(
             defaultValue,
             IncludeSchemaUri: false,
             inferenceOptions.DisallowAdditionalProperties,
-            inferenceOptions.IncludeTypeInEnumSchemas);
+            inferenceOptions.IncludeTypeInEnumSchemas,
+            inferenceOptions.RequireAllProperties,
+            inferenceOptions.FilterDisallowedKeywords);
 
         return GetJsonSchemaCached(serializerOptions, key);
     }
@@ -154,7 +163,9 @@ public static JsonElement CreateJsonSchema(
             defaultValue,
             inferenceOptions.IncludeSchemaKeyword,
             inferenceOptions.DisallowAdditionalProperties,
-            inferenceOptions.IncludeTypeInEnumSchemas);
+            inferenceOptions.IncludeTypeInEnumSchemas,
+            inferenceOptions.RequireAllProperties,
+            inferenceOptions.FilterDisallowedKeywords);
 
         return GetJsonSchemaCached(serializerOptions, key);
     }
@@ -242,6 +253,7 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
             const string PatternPropertyName = "pattern";
             const string EnumPropertyName = "enum";
             const string PropertiesPropertyName = "properties";
+            const string RequiredPropertyName = "required";
             const string AdditionalPropertiesPropertyName = "additionalProperties";
             const string DefaultPropertyName = "default";
             const string RefPropertyName = "$ref";
@@ -275,11 +287,35 @@ JsonNode TransformSchemaNode(JsonSchemaExporterContext ctx, JsonNode schema)
                 }
 
                 // Disallow additional properties in object schemas
-                if (key.DisallowAdditionalProperties && objSchema.ContainsKey(PropertiesPropertyName) && !objSchema.ContainsKey(AdditionalPropertiesPropertyName))
+                if (key.DisallowAdditionalProperties &&
+                    objSchema.ContainsKey(PropertiesPropertyName) &&
+                    !objSchema.ContainsKey(AdditionalPropertiesPropertyName))
                 {
                     objSchema.Add(AdditionalPropertiesPropertyName, (JsonNode)false);
                 }
 
+                // Mark all properties as required
+                if (key.RequireAllProperties &&
+                    objSchema.TryGetPropertyValue(PropertiesPropertyName, out JsonNode? properties) &&
+                    properties is JsonObject propertiesObj)
+                {
+                    _ = objSchema.TryGetPropertyValue(RequiredPropertyName, out JsonNode? required);
+                    if (required is not JsonArray { } requiredArray || requiredArray.Count != propertiesObj.Count)
+                    {
+                        requiredArray = [.. propertiesObj.Select(prop => prop.Key)];
+                        objSchema[RequiredPropertyName] = requiredArray;
+                    }
+                }
+
+                // Filter potentially disallowed keywords.
+                if (key.FilterDisallowedKeywords)
+                {
+                    foreach (string keyword in _schemaKeywordsDisallowedByAIVendors)
+                    {
+                        _ = objSchema.Remove(keyword);
+                    }
+                }
+
                 // Some consumers of the JSON schema, including Ollama as of v0.3.13, don't understand
                 // schemas with "type": [...], and only understand "type" being a single value.
                 // STJ represents .NET integer types as ["string", "integer"], which will then lead to an error.

src/Libraries/Microsoft.Extensions.AI/Functions/AIFunctionFactory.cs

@@ -189,7 +189,7 @@ static bool IsAsyncMethod(MethodInfo method)
             bool sawAIContextParameter = false;
             for (int i = 0; i < parameters.Length; i++)
             {
-                if (GetParameterMarshaller(options.SerializerOptions, parameters[i], ref sawAIContextParameter, out _parameterMarshallers[i]) is AIFunctionParameterMetadata parameterView)
+                if (GetParameterMarshaller(options, parameters[i], ref sawAIContextParameter, out _parameterMarshallers[i]) is AIFunctionParameterMetadata parameterView)
                 {
                     parameterMetadata?.Add(parameterView);
                 }
@@ -209,7 +209,7 @@ static bool IsAsyncMethod(MethodInfo method)
                 {
                     ParameterType = returnType,
                     Description = method.ReturnParameter.GetCustomAttribute<DescriptionAttribute>(inherit: true)?.Description,
-                    Schema = AIJsonUtilities.CreateJsonSchema(returnType, serializerOptions: options.SerializerOptions),
+                    Schema = AIJsonUtilities.CreateJsonSchema(returnType, serializerOptions: options.SerializerOptions, inferenceOptions: options.SchemaCreateOptions),
                 },
                 AdditionalProperties = options.AdditionalProperties ?? EmptyReadOnlyDictionary<string, object?>.Instance,
                 JsonSerializerOptions = options.SerializerOptions,
@@ -272,7 +272,7 @@ static bool IsAsyncMethod(MethodInfo method)
         /// Gets a delegate for handling the marshaling of a parameter.
         /// </summary>
         private static AIFunctionParameterMetadata? GetParameterMarshaller(
-            JsonSerializerOptions options,
+            AIFunctionFactoryCreateOptions options,
             ParameterInfo parameter,
             ref bool sawAIFunctionContext,
             out Func<IReadOnlyDictionary<string, object?>, AIFunctionContext?, object?> marshaller)
@@ -302,7 +302,7 @@ static bool IsAsyncMethod(MethodInfo method)
 
             // Resolve the contract used to marshal the value from JSON -- can throw if not supported or not found.
             Type parameterType = parameter.ParameterType;
-            JsonTypeInfo typeInfo = options.GetTypeInfo(parameterType);
+            JsonTypeInfo typeInfo = options.SerializerOptions.GetTypeInfo(parameterType);
 
             // Create a marshaller that simply looks up the parameter by name in the arguments dictionary.
             marshaller = (IReadOnlyDictionary<string, object?> arguments, AIFunctionContext? _) =>
@@ -325,7 +325,7 @@ static bool IsAsyncMethod(MethodInfo method)
 #pragma warning disable CA1031 // Do not catch general exception types
                         try
                         {
-                            string json = JsonSerializer.Serialize(value, options.GetTypeInfo(value.GetType()));
+                            string json = JsonSerializer.Serialize(value, options.SerializerOptions.GetTypeInfo(value.GetType()));
                             return JsonSerializer.Deserialize(json, typeInfo);
                         }
                         catch
@@ -361,7 +361,8 @@ static bool IsAsyncMethod(MethodInfo method)
                     description,
                     parameter.HasDefaultValue,
                     parameter.DefaultValue,
-                    options)
+                    options.SerializerOptions,
+                    options.SchemaCreateOptions)
             };
         }
 

src/Libraries/Microsoft.Extensions.AI/Functions/AIFunctionFactoryCreateOptions.cs

@@ -16,6 +16,7 @@ namespace Microsoft.Extensions.AI;
 public sealed class AIFunctionFactoryCreateOptions
 {
     private JsonSerializerOptions _options = AIJsonUtilities.DefaultOptions;
+    private AIJsonSchemaCreateOptions _schemaCreateOptions = AIJsonSchemaCreateOptions.Default;
 
     /// <summary>
     /// Initializes a new instance of the <see cref="AIFunctionFactoryCreateOptions"/> class.
@@ -31,6 +32,15 @@ public JsonSerializerOptions SerializerOptions
         set => _options = Throw.IfNull(value);
     }
 
+    /// <summary>
+    /// Gets or sets the <see cref="AIJsonSchemaCreateOptions"/> governing the generation of JSON schemas for the function.
+    /// </summary>
+    public AIJsonSchemaCreateOptions SchemaCreateOptions
+    {
+        get => _schemaCreateOptions;
+        set => _schemaCreateOptions = Throw.IfNull(value);
+    }
+
     /// <summary>Gets or sets the name to use for the function.</summary>
     /// <value>
     /// The name to use for the function. The default value is a name derived from the method represented by the passed <see cref="Delegate"/> or <see cref="MethodInfo"/>.