Fix empty Tools collection when loading PromptAgent from YAML

agentschema-emitter/src/templates/csharp/file.cs.njk

@@ -76,6 +76,12 @@ public{% if node.isAbstract %} abstract{% endif %} class {{ node.typeName.name }
     {
         var result = new List<{{ collection.prop.typeName.name }}>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -107,6 +113,11 @@ public{% if node.isAbstract %} abstract{% endif %} class {{ node.typeName.name }
                 {
                     result.Add({{ collection.prop.typeName.name }}.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add({{ collection.prop.typeName.name }}.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

agentschema-emitter/src/templates/csharp/utils.cs.njk

@@ -397,4 +397,43 @@ internal static class Utils
 
         return dict;
     }
+
+    /// <summary>
+    /// Normalizes a YamlDotNet Dictionary&lt;object, object&gt; to Dictionary&lt;string, object?&gt;,
+    /// recursively normalizing all nested values.
+    /// </summary>
+    /// <param name="dict">The YamlDotNet dictionary to normalize.</param>
+    /// <returns>A normalized Dictionary&lt;string, object?&gt;.</returns>
+    public static Dictionary<string, object?> NormalizeDictionary(this Dictionary<object, object> dict)
+    {
+        var result = new Dictionary<string, object?>();
+        foreach (var kvp in dict)
+        {
+            result[kvp.Key?.ToString() ?? ""] = NormalizeValue(kvp.Value);
+        }
+        return result;
+    }
+
+    /// <summary>
+    /// Recursively normalizes a value from YamlDotNet deserialization,
+    /// converting Dictionary&lt;object, object&gt; to Dictionary&lt;string, object?&gt;
+    /// and normalizing items within lists.
+    /// </summary>
+    /// <param name="value">The value to normalize.</param>
+    /// <returns>The normalized value.</returns>
+    public static object? NormalizeValue(this object? value)
+    {
+        if (value is Dictionary<object, object> dictObjObj)
+            return dictObjObj.NormalizeDictionary();
+
+        if (value is IEnumerable<object> enumerable)
+        {
+            var list = new List<object?>();
+            foreach (var item in enumerable)
+                list.Add(NormalizeValue(item));
+            return list;
+        }
+
+        return value;
+    }
 }

runtime/csharp/AgentSchema.Tests/PromptAgentToolsYamlTests.cs

@@ -0,0 +1,99 @@
+// Copyright (c) Microsoft. All rights reserved.
+using Xunit;
+
+#pragma warning disable IDE0130
+namespace AgentSchema;
+#pragma warning restore IDE0130
+
+/// <summary>
+/// Regression tests verifying that tools are correctly deserialized from YAML.
+/// YamlDotNet 16.x deserializes nested YAML mappings as Dictionary&lt;object, object&gt;
+/// rather than Dictionary&lt;string, object?&gt;, which previously caused the Tools
+/// collection to always be empty after loading from YAML.
+/// </summary>
+public class PromptAgentToolsYamlTests
+{
+    [Fact]
+    public void LoadYaml_ListFormat_ToolsAreDeserializedCorrectly()
+    {
+        string yaml = """
+kind: prompt
+name: my-agent
+model: gpt-4o
+template: Hello
+tools:
+  - name: search
+    kind: function
+    description: Search the web
+""";
+
+        var agent = AgentDefinition.FromYaml(yaml) as PromptAgent;
+
+        Assert.NotNull(agent);
+        Assert.NotNull(agent.Tools);
+        Assert.NotEmpty(agent.Tools);
+        Assert.Single(agent.Tools);
+        Assert.Equal("search", agent.Tools[0].Name);
+        Assert.Equal("function", agent.Tools[0].Kind);
+        Assert.Equal("Search the web", agent.Tools[0].Description);
+    }
+
+    [Fact]
+    public void LoadYaml_DictionaryFormat_ToolsAreDeserializedCorrectly()
+    {
+        string yaml = """
+kind: prompt
+name: my-agent
+model: gpt-4o
+template: Hello
+tools:
+  search:
+    kind: function
+    description: Search the web
+  calculate:
+    kind: function
+    description: Run a calculation
+""";
+
+        var agent = AgentDefinition.FromYaml(yaml) as PromptAgent;
+
+        Assert.NotNull(agent);
+        Assert.NotNull(agent.Tools);
+        Assert.NotEmpty(agent.Tools);
+        Assert.Equal(2, agent.Tools.Count);
+
+        var searchTool = agent.Tools.FirstOrDefault(t => t.Name == "search");
+        Assert.NotNull(searchTool);
+        Assert.Equal("function", searchTool.Kind);
+        Assert.Equal("Search the web", searchTool.Description);
+
+        var calcTool = agent.Tools.FirstOrDefault(t => t.Name == "calculate");
+        Assert.NotNull(calcTool);
+        Assert.Equal("function", calcTool.Kind);
+        Assert.Equal("Run a calculation", calcTool.Description);
+    }
+
+    [Fact]
+    public void LoadYaml_ListFormat_MultipleTool_CountIsCorrect()
+    {
+        string yaml = """
+kind: prompt
+name: my-agent
+model: gpt-4o
+template: Hello
+tools:
+  - name: search
+    kind: function
+    description: Search the web
+  - name: calculate
+    kind: function
+    description: Run a calculation
+""";
+
+        var agent = AgentDefinition.FromYaml(yaml) as PromptAgent;
+
+        Assert.NotNull(agent);
+        Assert.NotNull(agent.Tools);
+        Assert.Equal(2, agent.Tools.Count);
+    }
+}

runtime/csharp/AgentSchema/AgentManifest.cs

@@ -142,6 +142,12 @@ public static IList<Resource> LoadResources(object data, LoadContext? context)
     {
         var result = new List<Resource>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -173,6 +179,11 @@ public static IList<Resource> LoadResources(object data, LoadContext? context)
                 {
                     result.Add(Resource.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(Resource.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

runtime/csharp/AgentSchema/ContainerAgent.cs

@@ -123,6 +123,12 @@ public static IList<ProtocolVersionRecord> LoadProtocols(object data, LoadContex
     {
         var result = new List<ProtocolVersionRecord>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -154,6 +160,11 @@ public static IList<ProtocolVersionRecord> LoadProtocols(object data, LoadContex
                 {
                     result.Add(ProtocolVersionRecord.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(ProtocolVersionRecord.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 
@@ -168,6 +179,12 @@ public static IList<EnvironmentVariable> LoadEnvironmentVariables(object data, L
     {
         var result = new List<EnvironmentVariable>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -199,6 +216,11 @@ public static IList<EnvironmentVariable> LoadEnvironmentVariables(object data, L
                 {
                     result.Add(EnvironmentVariable.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(EnvironmentVariable.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

runtime/csharp/AgentSchema/ObjectProperty.cs

@@ -82,6 +82,12 @@ public static IList<Property> LoadProperties(object data, LoadContext? context)
     {
         var result = new List<Property>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -113,6 +119,11 @@ public static IList<Property> LoadProperties(object data, LoadContext? context)
                 {
                     result.Add(Property.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(Property.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

runtime/csharp/AgentSchema/PromptAgent.cs

@@ -123,6 +123,12 @@ public static IList<Tool> LoadTools(object data, LoadContext? context)
     {
         var result = new List<Tool>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -154,6 +160,11 @@ public static IList<Tool> LoadTools(object data, LoadContext? context)
                 {
                     result.Add(Tool.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(Tool.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

runtime/csharp/AgentSchema/PropertySchema.cs

@@ -92,6 +92,12 @@ public static IList<Property> LoadProperties(object data, LoadContext? context)
     {
         var result = new List<Property>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -123,6 +129,11 @@ public static IList<Property> LoadProperties(object data, LoadContext? context)
                 {
                     result.Add(Property.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(Property.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }
 

runtime/csharp/AgentSchema/Tool.cs

@@ -101,6 +101,12 @@ public static IList<Binding> LoadBindings(object data, LoadContext? context)
     {
         var result = new List<Binding>();
 
+        // Normalize YamlDotNet's Dictionary<object, object> to Dictionary<string, object?>
+        if (data is Dictionary<object, object> rawYamlDict)
+        {
+            data = rawYamlDict.NormalizeDictionary();
+        }
+
         if (data is Dictionary<string, object?> dict)
         {
             // Convert named dictionary to list
@@ -132,6 +138,11 @@ public static IList<Binding> LoadBindings(object data, LoadContext? context)
                 {
                     result.Add(Binding.Load(itemDict, context));
                 }
+                else if (item is Dictionary<object, object> yamlItemDict)
+                {
+                    // Handle YamlDotNet's Dictionary<object, object> list items
+                    result.Add(Binding.Load(yamlItemDict.NormalizeDictionary(), context));
+                }
             }
         }