Added tool calling support (#731)

Co-authored-by: krut_ni <nils.kruthoff@dlr.de>
Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/ToolCallingSystem/ToolParameterSchemaBuilder.cs

@@ -0,0 +1,73 @@
+using System.Text.Json;
+using System.Text.Json.Nodes;
+
+namespace AIStudio.Tools.ToolCallingSystem;
+
+/// <summary>
+/// Builds the JSON Schema describing a tool's arguments.
+/// </summary>
+/// <remarks>
+/// The schema is written the ordinary JSON Schema way: an optional argument is simply absent
+/// from the required list. Providers whose APIs want it differently get it converted in their
+/// adapter — OpenAI's strict mode, for instance, wants every argument required and the optional
+/// ones nullable instead.<br/><br/>
+/// Argument names come in as constants that the reading code shares, so the schema and the code
+/// pulling the values apart cannot drift.
+/// </remarks>
+public sealed class ToolParameterSchemaBuilder
+{
+    private readonly JsonObject properties = new();
+    private readonly List<string> requiredNames = [];
+
+    public static ToolParameterSchemaBuilder Create() => new();
+
+    public ToolParameterSchemaBuilder RequiredString(string name, string description) => this.Add(name, "string", description, isRequired: true);
+
+    public ToolParameterSchemaBuilder OptionalString(string name, string description) => this.Add(name, "string", description, isRequired: false);
+
+    public ToolParameterSchemaBuilder RequiredInteger(string name, string description) => this.Add(name, "integer", description, isRequired: true);
+
+    public ToolParameterSchemaBuilder OptionalInteger(string name, string description) => this.Add(name, "integer", description, isRequired: false);
+
+    public ToolParameterSchemaBuilder RequiredEnum(string name, string description, params string[] allowedValues) => this.Add(name, "string", description, isRequired: true, allowedValues);
+
+    public ToolParameterSchemaBuilder OptionalEnum(string name, string description, params string[] allowedValues) => this.Add(name, "string", description, isRequired: false, allowedValues);
+
+    /// <summary>
+    /// Produces the finished schema.
+    /// </summary>
+    /// <remarks>
+    /// Additional properties are refused: an argument AI Studio does not know about is a
+    /// misunderstanding, not something to pass on to a tool.
+    /// </remarks>
+    public JsonElement Build()
+    {
+        var schema = new JsonObject
+        {
+            ["type"] = "object",
+            ["properties"] = this.properties.DeepClone(),
+            ["required"] = new JsonArray([..this.requiredNames.Select(name => JsonValue.Create(name))]),
+            ["additionalProperties"] = false,
+        };
+
+        return JsonSerializer.Deserialize<JsonElement>(schema.ToJsonString());
+    }
+
+    private ToolParameterSchemaBuilder Add(string name, string jsonType, string description, bool isRequired, IReadOnlyList<string>? allowedValues = null)
+    {
+        var property = new JsonObject
+        {
+            ["type"] = jsonType,
+            ["description"] = description,
+        };
+
+        if (allowedValues is { Count: > 0 })
+            property["enum"] = new JsonArray([..allowedValues.Select(value => JsonValue.Create(value))]);
+
+        this.properties[name] = property;
+        if (isRequired)
+            this.requiredNames.Add(name);
+
+        return this;
+    }
+}