.Net: Kernel function arguments cannot be of type Array<Enum>

[EdenTanami]

Describe the bug
Kernel function with argument of type Enum[] throws on invocation.

I am writing a kernel function that finds toys with the following signature:
public string FindToy(Color[] colors) {...}
public enum Color { Blue, Red, Green }
Then I ask in the chat question to invoke my function.

• This is the parameters schema sent to openAI sdk:
  {{"type":"object","required":["colors"],"properties":{"colors":{"type":"array","items":{"enum":["Blue","Red","Green"]}}}}}
• This is the arguments in the model responses' ToolCalls:
  "{"colors":["Blue","Red"]}"
• When invoking in this function SK throws this exception:
  Function failed. Error: Object of type 'System.String' cannot be converted to type 'SKCopilotToolkit.Sample.SampleMockScenario.Plugins.ToysPlugin+Color[]'.

To Reproduce
Steps to reproduce the behavior:

1. Register the function with the following signature to the kernel:
   [KernelFunction("FindToy")] public string FindToy(Color[] colors)
2. Ask the chat completion service for toys in some colors
3. examine the errors in the logs

Expected behavior
The function will be called with array of Enum values [Blue, Red]

Platform

• OS: Windows
• IDE: Visual Studio,
• Language: C#
• Source: SK NuGet package version 1.5.0

[stephentoub]

cc: @SergeyMenshykh

[SergeyMenshykh]

Hi @EdenTanami, thank you for reporting this issue. Here are two options you can use until a long-term solution is found:

1. Register the JsonStringEnumConverter converter for your enum. For example - [JsonConverter(typeof(JsonStringEnumConverter))]
2. Modify your function parameter type from Color[] to string[].

[SergeyMenshykh]

[Context] Option 1 will not work in cases where there is no access to the enum to mark it with the attribute. A possible solution could be allowing consumer code to specify JsonSerializerOptions for controlling tool call argument deserialization behavior.