diff --git a/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunOptions.cs b/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunOptions.cs
index c6a64915cf..7262979207 100644
--- a/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunOptions.cs
+++ b/dotnet/src/Microsoft.Agents.AI.Abstractions/AgentRunOptions.cs
@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System;
+using Microsoft.Extensions.AI;
 using Microsoft.Shared.Diagnostics;
 
 namespace Microsoft.Agents.AI;
@@ -32,6 +33,7 @@ public class AgentRunOptions
         _ = Throw.IfNull(options);
         this.ContinuationToken = options.ContinuationToken;
         this.AllowBackgroundResponses = options.AllowBackgroundResponses;
+        this.AdditionalProperties = options.AdditionalProperties?.Clone();
     }
 
     /// <summary>
@@ -74,4 +76,18 @@ public class AgentRunOptions
     /// </para>
     /// </remarks>
     public bool? AllowBackgroundResponses { get; set; }
+
+    /// <summary>
+    /// Gets or sets additional properties associated with these options.
+    /// </summary>
+    /// <value>
+    /// An <see cref="AdditionalPropertiesDictionary"/> containing custom properties,
+    /// or <see langword="null"/> if no additional properties are present.
+    /// </value>
+    /// <remarks>
+    /// Additional properties provide a way to include custom metadata or provider-specific
+    /// information that doesn't fit into the standard options schema. This is useful for
+    /// preserving implementation-specific details or extending the options with custom data.
+    /// </remarks>
+    public AdditionalPropertiesDictionary? AdditionalProperties { get; set; }
 }
diff --git a/dotnet/tests/Microsoft.Agents.AI.Abstractions.UnitTests/AgentRunOptionsTests.cs b/dotnet/tests/Microsoft.Agents.AI.Abstractions.UnitTests/AgentRunOptionsTests.cs
index 40901a4969..32560949fb 100644
--- a/dotnet/tests/Microsoft.Agents.AI.Abstractions.UnitTests/AgentRunOptionsTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.Abstractions.UnitTests/AgentRunOptionsTests.cs
@@ -18,7 +18,12 @@ public class AgentRunOptionsTests
         var options = new AgentRunOptions
         {
             ContinuationToken = new object(),
-            AllowBackgroundResponses = true
+            AllowBackgroundResponses = true,
+            AdditionalProperties = new AdditionalPropertiesDictionary
+            {
+                ["key1"] = "value1",
+                ["key2"] = 42
+            }
         };
 
         // Act
@@ -28,6 +33,10 @@ public class AgentRunOptionsTests
         Assert.NotNull(clone);
         Assert.Same(options.ContinuationToken, clone.ContinuationToken);
         Assert.Equal(options.AllowBackgroundResponses, clone.AllowBackgroundResponses);
+        Assert.NotNull(clone.AdditionalProperties);
+        Assert.NotSame(options.AdditionalProperties, clone.AdditionalProperties);
+        Assert.Equal("value1", clone.AdditionalProperties["key1"]);
+        Assert.Equal(42, clone.AdditionalProperties["key2"]);
     }
 
     [Fact]
@@ -42,7 +51,12 @@ public class AgentRunOptionsTests
         var options = new AgentRunOptions
         {
             ContinuationToken = ResponseContinuationToken.FromBytes(new byte[] { 1, 2, 3 }),
-            AllowBackgroundResponses = true
+            AllowBackgroundResponses = true,
+            AdditionalProperties = new AdditionalPropertiesDictionary
+            {
+                ["key1"] = "value1",
+                ["key2"] = 42
+            }
         };
 
         // Act
@@ -54,5 +68,13 @@ public class AgentRunOptionsTests
         Assert.NotNull(deserialized);
         Assert.Equivalent(ResponseContinuationToken.FromBytes(new byte[] { 1, 2, 3 }), deserialized!.ContinuationToken);
         Assert.Equal(options.AllowBackgroundResponses, deserialized.AllowBackgroundResponses);
+        Assert.NotNull(deserialized.AdditionalProperties);
+        Assert.Equal(2, deserialized.AdditionalProperties.Count);
+        Assert.True(deserialized.AdditionalProperties.TryGetValue("key1", out object? value1));
+        Assert.IsType<JsonElement>(value1);
+        Assert.Equal("value1", ((JsonElement)value1!).GetString());
+        Assert.True(deserialized.AdditionalProperties.TryGetValue("key2", out object? value2));
+        Assert.IsType<JsonElement>(value2);
+        Assert.Equal(42, ((JsonElement)value2!).GetInt32());
     }
 }
diff --git a/python/packages/core/agent_framework/_mcp.py b/python/packages/core/agent_framework/_mcp.py
index 50f6a91c2e..873b7f04cc 100644
--- a/python/packages/core/agent_framework/_mcp.py
+++ b/python/packages/core/agent_framework/_mcp.py
@@ -19,7 +19,7 @@ from mcp.client.websocket import websocket_client
 from mcp.shared.context import RequestContext
 from mcp.shared.exceptions import McpError
 from mcp.shared.session import RequestResponder
-from pydantic import BaseModel, create_model
+from pydantic import BaseModel, Field, create_model
 
 from ._tools import AIFunction, HostedMCPSpecificApproval
 from ._types import ChatMessage, Contents, DataContent, Role, TextContent, UriContent
@@ -224,13 +224,20 @@ def _get_input_model_from_mcp_tool(tool: types.Tool) -> type[BaseModel]:
         prop_details = json.loads(prop_details) if isinstance(prop_details, str) else prop_details
 
         python_type = resolve_type(prop_details)
+        description = prop_details.get("description", "")
 
         # Create field definition for create_model
         if prop_name in required:
-            field_definitions[prop_name] = (python_type, ...)
+            field_definitions[prop_name] = (
+                (python_type, Field(description=description)) if description else (python_type, ...)
+            )
         else:
             default_value = prop_details.get("default", None)
-            field_definitions[prop_name] = (python_type, default_value)
+            field_definitions[prop_name] = (
+                (python_type, Field(default=default_value, description=description))
+                if description
+                else (python_type, default_value)
+            )
 
     return create_model(f"{tool.name}_input", **field_definitions)