core[patch]: Adds option for more verbose parsing errors

langchain-core/src/tools/index.ts

@@ -46,6 +46,12 @@ export interface ToolParams extends BaseLangChainParams {
    * @default "content"
    */
   responseFormat?: ResponseFormat;
+  /**
+   * Whether to show full details in the thrown parsing errors.
+   *
+   * @default false
+   */
+  verboseParsingErrors?: boolean;
 }
 
 /**
@@ -121,6 +127,9 @@ export abstract class StructuredTool<
 
   returnDirect = false;
 
+  // TODO: Make default in 0.3
+  verboseParsingErrors = false;
+
   get lc_namespace() {
     return ["langchain", "tools"];
   }
@@ -139,6 +148,8 @@ export abstract class StructuredTool<
   constructor(fields?: ToolParams) {
     super(fields ?? {});
 
+    this.verboseParsingErrors =
+      fields?.verboseParsingErrors ?? this.verboseParsingErrors;
     this.responseFormat = fields?.responseFormat ?? this.responseFormat;
   }
 
@@ -205,11 +216,13 @@ export abstract class StructuredTool<
     let parsed;
     try {
       parsed = await this.schema.parseAsync(arg);
-    } catch (e) {
-      throw new ToolInputParsingException(
-        `Received tool input did not match expected schema`,
-        JSON.stringify(arg)
-      );
+      // eslint-disable-next-line @typescript-eslint/no-explicit-any
+    } catch (e: any) {
+      let message = `Received tool input did not match expected schema`;
+      if (this.verboseParsingErrors) {
+        message = `${message}\nDetails: ${e.message}`;
+      }
+      throw new ToolInputParsingException(message, JSON.stringify(arg));
     }
 
     const config = parseCallbackConfigArg(configArg);

langchain-core/src/tools/tests/tools.test.ts

@@ -222,3 +222,39 @@ test("Tool input typing is enforced", async () => {
   const res3 = await weatherTool3.invoke("blah");
   expect(res3).toEqual("Sunny");
 });
+
+test("Tool can throw detailed errors", async () => {
+  const weatherSchema = z.object({
+    location: z.string(),
+  });
+
+  const stringTool = tool(
+    (input) => {
+      return JSON.stringify(input);
+    },
+    {
+      name: "string_tool",
+      description: "A tool that appends 'a' to the input string",
+      schema: weatherSchema,
+      verboseParsingErrors: true,
+    }
+  );
+
+  await expect(
+    stringTool.invoke({
+      // @ts-expect-error Testing parsing errors
+      location: 8,
+    })
+  ).rejects.toThrow(`Received tool input did not match expected schema
+Details: [
+  {
+    "code": "invalid_type",
+    "expected": "string",
+    "received": "number",
+    "path": [
+      "location"
+    ],
+    "message": "Expected string, received number"
+  }
+]`);
+});