Tool doesnt invoke

[lakshya29154]

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Example Code

@Tool({
   name:'pdfAnswerTool',
   description:'Trigger this tool when you receive the object which consist or url and question',
   schema: z.object({
    input: z.object({
      url: z.string(),
      question: z.string(),
    }),
  }),
 })
 async pdfAnswer({input}):Promise<any>{
  console.log("i am in pdfAnswer tool",input)
 }

Description

I am sending the api with payload
{
"input": {
"url": "/home/lib/application/pdf",
"question": "I am from pdf"
}
}

But my tool is not invoking how to invoke this tool

System Info

windows
node - 20

[dosubot[bot]]

To invoke a tool in LangChainJS, you should use the invoke method on the tool instance. It seems like you are using a decorator pattern, but the invocation process requires calling the invoke method explicitly. Here's how you can do it:

1. Ensure that your tool is properly instantiated.
2. Use the invoke method to execute the tool with the required input.

Here's an example of how you might set this up:

// Assuming you have a tool instance created somewhere in your code
const toolInstance = new YourToolClass(); // Replace with your actual tool class

// Invoke the tool with the input
const result = await toolInstance.invoke({
    input: {
        url: "/home/lib/application/pdf",
        question: "I am from pdf"
    }
});

console.log(result);

Make sure that your tool class is correctly set up to handle the invoke method. If you are using a custom tool, ensure that it follows the pattern for tool creation and invocation as described in the LangChainJS documentation ^[1][2].

To continue talking to Dosu, mention @dosu.

[lakshya29154]

@dosu I am sending from frontend through api and in backend I have created a controller import { Controller, Post, Body, Get } from '@nestjs/common';
import { LangChainService } from './langchain.service';

@controller('langchain')
export class LangChainController {
constructor(private readonly langChainService: LangChainService) {}

@get('invoke')
async test()
{
const testAPI = {
message: 'GET REQUEST SUCCESSFULLY COMPLETED',
timestamp: Date.now(),
};
return testAPI;
}
@post('invoke')
async invokeAgent(@Body('input') input: any) {
console.log("input",input)
const agentExecutor = this.langChainService.getAgentExecutor();
const result = await agentExecutor.invoke({
input,
});
return result.output;
}

}

[dosubot[bot]]

To ensure that your tool is invoked correctly from the frontend through an API in a NestJS backend, you need to verify a few things:

1. Ensure Correct Input Structure: Make sure the input structure sent from the frontend matches what the invoke method expects. The input should be an object with an input property, as shown in your invokeAgent method.

2. Check Tool Initialization: Ensure that the LangChainService class correctly initializes the agentExecutor and that the getAgentExecutor method returns a properly configured instance of AgentExecutor.

3. Verify Tool Configuration: Ensure that the tools used by the agentExecutor are correctly configured and available. If the tool is not properly set up, it might not be invoked.

4. Error Handling: Implement error handling to catch any issues during the invocation process. This can help identify if there are any runtime errors or misconfigurations.

Here's a basic example of how your controller and service might be structured:

// langchain.service.ts
import { Injectable } from '@nestjs/common';
import { AgentExecutor } from 'langchain'; // Adjust import based on your setup

@Injectable()
export class LangChainService {
  getAgentExecutor(): AgentExecutor {
    // Initialize and return the AgentExecutor with necessary tools
    const agentExecutor = new AgentExecutor({
      // Configure your agent and tools here
    });
    return agentExecutor;
  }
}

// langchain.controller.ts
import { Controller, Post, Body, Get } from '@nestjs/common';
import { LangChainService } from './langchain.service';

@Controller('langchain')
export class LangChainController {
  constructor(private readonly langChainService: LangChainService) {}

  @Get('invoke')
  async test() {
    const testAPI = {
      message: 'GET REQUEST SUCCESSFULLY COMPLETED',
      timestamp: Date.now(),
    };
    return testAPI;
  }

  @Post('invoke')
  async invokeAgent(@Body('input') input: any) {
    console.log("input", input);
    const agentExecutor = this.langChainService.getAgentExecutor();
    try {
      const result = await agentExecutor.invoke({ input });
      return result.output;
    } catch (error) {
      console.error("Error invoking tool:", error);
      throw error; // Or handle the error as needed
    }
  }
}

Ensure that your LangChainService is correctly setting up the AgentExecutor with the necessary tools and configurations. If the tool is still not invoking, check for any errors in the console or logs that might indicate what is going wrong.

To continue talking to Dosu, mention @dosu.