anthropic[patch]: Force tool call by name in withStructuredOutput

libs/langchain-anthropic/src/chat_models.ts

@@ -1026,7 +1026,10 @@ export class ChatAnthropicMessages<
     }
     const llm = this.bind({
       tools,
-      tool_choice: "any",
+      tool_choice: {
+        type: "tool",
+        name: functionName,
+      },
     } as Partial<CallOptions>);
 
     if (!includeRaw) {

libs/langchain-anthropic/src/tests/chat_models-tools.int.test.ts

@@ -362,3 +362,27 @@ test("bindTools accepts openai formatted tool", async () => {
   }
   expect(tool_calls[0].name).toBe("get_weather");
 });
+
+test("withStructuredOutput will always force tool usage", async () => {
+  const weatherTool = z
+    .object({
+      location: z.string().describe("The name of city to get the weather for."),
+    })
+    .describe(
+      "Get the weather of a specific location and return the temperature in Celsius."
+    );
+  const modelWithTools = model.withStructuredOutput(weatherTool, {
+    name: "get_weather",
+    includeRaw: true,
+  });
+  const response = await modelWithTools.invoke(
+    "What is the sum of 271623 and 281623? It is VERY important you use a calculator tool to give me the answer."
+  );
+
+  if (!("tool_calls" in response.raw)) {
+    throw new Error("Tool call not found in response");
+  }
+  const castMessage = response.raw as AIMessage;
+  expect(castMessage.tool_calls).toHaveLength(1);
+  expect(castMessage.tool_calls?.[0].name).toBe("get_weather");
+});