feat(agent): make responseFormat.strict configurable to support optional tool parameters

libs/langchain/src/agents/nodes/AgentNode.ts

@@ -835,13 +835,18 @@ export class AgentNode<
      * check if the user requests a native schema output
      */
     if (structuredResponseFormat?.type === "native") {
+      const resolvedStrict =
+        preparedOptions?.modelSettings?.strict ??
+        structuredResponseFormat?.strategy?.strict ??
+        true;
+
       const jsonSchemaParams = {
         name: structuredResponseFormat.strategy.schema?.name ?? "extract",
         description: getSchemaDescription(
           structuredResponseFormat.strategy.schema
         ),
         schema: structuredResponseFormat.strategy.schema,
-        strict: true,
+        strict: resolvedStrict,
       };
 
       Object.assign(options, {
@@ -860,7 +865,7 @@ export class AgentNode<
           kwargs: { method: "json_schema" },
           schema: structuredResponseFormat.strategy.schema,
         },
-        strict: true,
+        strict: resolvedStrict,
       });
     }
 

libs/providers/langchain-openai/src/chat_models/responses.ts

@@ -73,7 +73,8 @@ export class ChatOpenAIResponses<
     let strict: boolean | undefined;
     if (options?.strict !== undefined) {
       strict = options.strict;
-    } else if (this.supportsStrictToolCalling !== undefined) {
+    }
+    if (strict === undefined && this.supportsStrictToolCalling !== undefined) {
       strict = this.supportsStrictToolCalling;
     }
 

libs/providers/langchain-openai/src/chat_models/tests/responses.strict.test.ts

@@ -0,0 +1,53 @@
+import { describe, it, expect } from "vitest";
+import { ChatOpenAIResponses } from "../responses.js";
+
+describe("strict tool-calling configuration", () => {
+  it("falls back to supportsStrictToolCalling when strict is undefined", () => {
+    const model = new ChatOpenAIResponses({
+      model: "gpt-4o",
+      supportsStrictToolCalling: true,
+    });
+
+    const params = model.invocationParams({
+      tools: [
+        {
+          type: "function",
+          function: {
+            name: "test_func",
+            description: "testing",
+            parameters: { type: "object", properties: {} },
+          },
+        },
+      ],
+    });
+
+    expect("strict" in params).toBe(false);
+
+    expect((params.tools as Array<{ strict?: boolean }>)[0].strict).toBe(true);
+  });
+
+  it("respects user-provided strict option", () => {
+    const model = new ChatOpenAIResponses({
+      model: "gpt-4o",
+      supportsStrictToolCalling: true,
+    });
+
+    const params = model.invocationParams({
+      strict: false,
+      tools: [
+        {
+          type: "function",
+          function: {
+            name: "test_func",
+            description: "testing",
+            parameters: { type: "object", properties: {} },
+          },
+        },
+      ],
+    });
+
+    expect("strict" in params).toBe(false);
+
+    expect((params.tools as Array<{ strict?: boolean }>)[0].strict).toBe(false);
+  });
+});