diff --git a/dotnet/src/Microsoft.Agents.AI/Skills/Programmatic/AgentInlineSkillScript.cs b/dotnet/src/Microsoft.Agents.AI/Skills/Programmatic/AgentInlineSkillScript.cs
index b640e08d8e6..cce582b1be4 100644
--- a/dotnet/src/Microsoft.Agents.AI/Skills/Programmatic/AgentInlineSkillScript.cs
+++ b/dotnet/src/Microsoft.Agents.AI/Skills/Programmatic/AgentInlineSkillScript.cs
@@ -99,7 +99,8 @@ private static AIFunctionArguments ConvertToFunctionArguments(JsonElement? argum
         if (arguments.Value.ValueKind != JsonValueKind.Object)
         {
             throw new InvalidOperationException(
-                $"Inline skill scripts expect arguments as a JSON object but received a JSON element of kind '{arguments.Value.ValueKind}'.");
+                $"Inline skill scripts expect arguments as a JSON object but received a JSON element of kind '{arguments.Value.ValueKind}'. " +
+                "Configure a custom argument marshaler on the skill to handle other argument formats.");
         }
 
         var dict = new Dictionary<string, object?>();
diff --git a/dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/SkillScriptArgumentMarshalerTests.cs b/dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/SkillScriptArgumentMarshalerTests.cs
index 325ba3f826c..bfc39ec3add 100644
--- a/dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/SkillScriptArgumentMarshalerTests.cs
+++ b/dotnet/tests/Microsoft.Agents.AI.UnitTests/AgentSkills/SkillScriptArgumentMarshalerTests.cs
@@ -99,6 +99,7 @@ public async Task DefaultMarshaler_StringArguments_ThrowsAsync()
         var ex = await Assert.ThrowsAsync<InvalidOperationException>(
             () => script.RunAsync(skill, element, null, CancellationToken.None));
         Assert.Contains("String", ex.Message);
+        Assert.Contains("custom argument marshaler", ex.Message);
     }
 
     [Fact]