Property 'a' does not exist on type 'ZodObject'

[falmanna]

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Example Code

import { z } from "zod";
import { tool } from "@langchain/core/tools";

const adderSchema = z.object({
  a: z.number(),
  b: z.number(),
});
const adderTool = tool(
  async (input): Promise<string> => {
    const sum = input.a + input.b;
    return `The sum of ${input.a} and ${input.b} is ${sum}`;
  },
  {
    name: "adder",
    description: "Adds two numbers together",
    schema: adderSchema,
  }
);

Description

I am moving my codbase from python to typescript, but I having a small problem with tool typing.
I am following the tools tutorial and I keep typescript getting this error in vscode.

Property 'a' does not exist on type 'ZodObject<{ a: ZodNumber; b: ZodNumber; }, "strip", ZodTypeAny, { a: number; b: number; }, { a: number; b: number; }>'.ts(2339)

Running the code is working fine, but I wonder what is the problem here?

System Info

npm

"@langchain/anthropic": "^0.3.6",
"@langchain/core": "^0.3.15",
"@langchain/langgraph": "^0.2.18",
"@langchain/ollama": "^0.1.0",
"@langchain/openai": "^0.3.11",
"zod": "^3.23.8"

[dosubot[bot]]

The error you're encountering, "Property 'a' does not exist on type 'ZodObject'", is likely due to TypeScript not inferring the correct type for the input parameter in your adderTool function. This can happen if TypeScript is unable to automatically infer the types from the Zod schema.

To resolve this, you can explicitly type the input parameter in your function to match the shape of the Zod schema. Here's how you can modify your code:

import { z } from "zod";
import { tool } from "@langchain/core/tools";

const adderSchema = z.object({
  a: z.number(),
  b: z.number(),
});

type AdderInput = z.infer<typeof adderSchema>;

const adderTool = tool(
  async (input: AdderInput): Promise<string> => {
    const sum = input.a + input.b;
    return `The sum of ${input.a} and ${input.b} is ${sum}`;
  },
  {
    name: "adder",
    description: "Adds two numbers together",
    schema: adderSchema,
  }
);

By using z.infer<typeof adderSchema>, you explicitly define the type of input to match the structure of your Zod schema, which should resolve the TypeScript error.

To continue talking to Dosu, mention @dosu.

[falmanna]

Tried this, I am getting this error on the tool function:

No overload matches this call.
  Overload 1 of 3, '(func: RunnableFunc<string, any>, fields: ToolWrapperParams<ZodString>): DynamicTool', gave the following error.
    Argument of type '(input: AdderInput) => Promise<string>' is not assignable to parameter of type 'RunnableFunc<string, any>'.
      Types of parameters 'input' and 'input' are incompatible.
        Type 'string' is not assignable to type '{ a: number; b: number; }'.
  Overload 2 of 3, '(func: RunnableFunc<any, any>, fields: ToolWrapperParams<ZodObjectAny>): DynamicStructuredTool<ZodObjectAny>', gave the following error.
    Type 'ZodObject<{ a: ZodNumber; b: ZodNumber; }, "strip", ZodTypeAny, { a: number; b: number; }, { a: number; b: number; }>' is not assignable to type 'ZodObject<any, any, any, any, { [x: string]: any; }>'.
      Types have separate declarations of a private property '_cached'.
  Overload 3 of 3, '(func: RunnableFunc<{ a: number; b: number; }, any>, fields: ToolWrapperParams<{ a: number; b: number; }>): DynamicStructuredTool<{ a: number; b: number; }>', gave the following error.
    Type 'ZodObject<{ a: ZodNumber; b: ZodNumber; }, "strip", ZodTypeAny, { a: number; b: number; }, { a: number; b: number; }>' is missing the following properties from type '{ a: number; b: number; }': a, bts(2769)
index.d.ts(246, 5): The expected type comes from property 'schema' which is declared here on type 'ToolWrapperParams<ZodObjectAny>'
index.d.ts(246, 5): The expected type comes from property 'schema' which is declared here on type 'ToolWrapperParams<{ a: number; b: number; }>'

[falmanna]

Okay, the error occurs if there are multiple versions of zod in the project

npm ls zod

Make sure to only have a single versino