Stream the tool calling rounds of the Anthropic messages API

app/MindWork AI Studio/Provider/Anthropic/AnthropicToolUse.cs

@@ -10,8 +10,19 @@ public sealed record AnthropicToolUse
 
     public JsonElement Input { get; init; }
 
+    /// <summary>
+    /// The arguments as they came off the wire, set only when they never parsed into an object.
+    /// </summary>
+    /// <remarks>
+    /// Only a streamed round can have these: the arguments arrive in fragments there, and a
+    /// stream which ends mid-fragment leaves text which is not an object. The block carries an
+    /// empty object in that case, because that is what may go back to the provider -- while the
+    /// call itself has to be rejected rather than run without the arguments it asked for.
+    /// </remarks>
+    public string? UnparsableArguments { get; init; }
+
     /// <summary>
     /// The arguments as JSON text, which is what the tool executor works with.
     /// </summary>
-    public string Arguments => this.Input.ValueKind is JsonValueKind.Undefined ? "{}" : this.Input.GetRawText();
+    public string Arguments => this.UnparsableArguments ?? (this.Input.ValueKind is JsonValueKind.Undefined ? "{}" : this.Input.GetRawText());
 }