feat: Add Gemini 3 support with ThinkingLevel and thought signatures

README.md

@@ -565,7 +565,9 @@ foreach (var tool in mcpTools)
 - Auto-reconnection support
 - Works with any MCP-compatible server (Node.js, Python, C#, etc.)
 
-**See [samples/McpIntegrationDemo](samples/McpIntegrationDemo) for complete examples.**
+**For detailed documentation and examples, see:**
+- **[MCP Integration Guide](https://github.com/gunpal5/Google_GenerativeAI/wiki/MCP-(Model-Context-Protocol)-Integration)** - Complete guide with configuration options, best practices, and troubleshooting
+- **[samples/McpIntegrationDemo](samples/McpIntegrationDemo)** - Working code examples
 
 ---
 ## Image Generation and Captioning

src/GenerativeAI/Constants/GoogleAIModels.cs

@@ -165,7 +165,19 @@ public static class GoogleAIModels
     /// Gemini Robotics-ER 1.5 Preview model name.
     /// </summary>
     public const string GeminiRoboticsEr15Preview = "models/gemini-robotics-er-1.5-preview";
-
+
+    /// <summary>
+    /// Gemini 3 Pro Preview model name.
+    /// Supports advanced thinking features with thought signatures for function calling.
+    /// </summary>
+    public const string Gemini3ProPreview = "models/gemini-3-pro-preview";
+
+    /// <summary>
+    /// Gemini 3 Flash Preview model name.
+    /// Supports advanced thinking features with thought signatures for function calling.
+    /// </summary>
+    public const string Gemini3FlashPreview = "models/gemini-3-flash-preview";
+
     /// <summary>
     /// The current Gemini Embedding model name.
     /// </summary>

src/GenerativeAI/Types/ContentGeneration/Common/Schema.cs

@@ -105,8 +105,9 @@ public Schema() : this("") { }
 
     /// <summary>
     /// Optional. Schema for additional properties not explicitly defined.
+    /// Note: This property is not supported by the Gemini API and is excluded from serialization.
     /// </summary>
-    [JsonPropertyName("additionalProperties")]
+    [JsonIgnore]
     public JsonNode? AdditionalProperties { get; set; }
 
     /// <summary>

src/GenerativeAI/Types/ContentGeneration/Config/GenerationConfig.cs

@@ -228,12 +228,42 @@ public class ThinkingConfig
     /// </summary>
     [JsonPropertyName("includeThoughts")]
     public bool? IncludeThoughts { get; set; }
-    
+
     /// <summary>
-    /// Indicates the thinking budget in tokens
+    /// Indicates the thinking budget in tokens.
     /// </summary>
     [JsonPropertyName("thinkingBudget")]
     public int? ThinkingBudget { get; set; }
+
+    /// <summary>
+    /// Controls the maximum depth of the model's internal reasoning process before it produces a response.
+    /// This is particularly relevant for Gemini 3 and later models.
+    /// </summary>
+    [JsonPropertyName("thinkingLevel")]
+    public ThinkingLevel? ThinkingLevel { get; set; }
+}
+
+/// <summary>
+/// Controls the depth of thinking/reasoning for models that support thinking features.
+/// Used with Gemini 3 and later models.
+/// </summary>
+public enum ThinkingLevel
+{
+    /// <summary>
+    /// Unspecified thinking level.
+    /// </summary>
+    THINKING_LEVEL_UNSPECIFIED,
+
+    /// <summary>
+    /// Low thinking level - faster responses with less deep reasoning.
+    /// </summary>
+    LOW,
+
+    /// <summary>
+    /// High thinking level - deeper reasoning with potentially slower responses.
+    /// Recommended for complex tasks.
+    /// </summary>
+    HIGH
 }
 
 /// <summary>