M.E.AI - Add support for string JsonElement parsing to primitive

[RogerBarreto]

Inspired in the change for Semantic Kernel

• .Net: Add JsonElement String to Primitive Implicit Conversion Support (SLM Function Calling) microsoft/semantic-kernel#9784

This change covers the lack of a property on jsonSerializationOptions.BooleanHandler = JsonBooleanHandling.AllowReadingFromString which allows SLMs to call functions when the JsonElement is provided as of kind == string when converting to boolean AIFunctions arguments.

This change improves function calling experience when using local models that send JSON string argument values (i.e: "brightness": "20" or "switch": "true") instead of the expected JSON type ("brightness": 20, "switch": true) for calling functions even when the schema is correctly providing the expected type.

i.e: Ollama running a Llama 3.2 SLM.

This pattern also follows the current behavior of the JsonSerializerOptions currently being used by the M.E.AI JsonSerializerDefaults.Web.

That by default converts string as numbers, similar would be expected for booleans.

https://github.com/dotnet/extensions/blob/c08e5ac737d0830ff83c1c5ae8b084e6fce2b538/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Defaults.cs#L31

JsonSerializerOptions options = new(JsonSerializerDefaults.Web)

[stephentoub]

I'm not clear on what this is trying to fix. Can you elaborate on the scenario?

cc: @eiriktsarpalis

[eiriktsarpalis]

The reported JSON schema for custom converters is always true. Please also update the AIJsonUtilities.CreateSchema method so that the schema returned when this converter is encountered matches that of boolean values, i.e. { "type" : "boolean" } This can be done by adding a check in the TransformSchemaNode delegate:

https://github.com/dotnet/extensions/blob/main/src/Libraries/Microsoft.Extensions.AI.Abstractions/Utilities/AIJsonUtilities.Schema.cs#L234

[RogerBarreto]

I'm not clear on what this is trying to fix. Can you elaborate on the scenario?

@stephentoub Added more context to the PR description.

[eiriktsarpalis]

Valid boolean values are at most 5 characters long. You can avoid pooling buffers if you just check the length of the input before stack allocating a buffer of length 5.

[stephentoub]

I don't know if we care, but if there was whitespace padding around the true/false, it could be longer than 5 chars. bool.Parse trims and thus will happily successfully parse e.g. " true ".

[stephentoub]

I'm not clear on what this is trying to fix. Can you elaborate on the scenario?

@stephentoub Added more context to the PR description.

Thanks. It became much clearer when the PR changed to just be about the boolean converter.