app/api/langchain-tools/http_get.ts

import { htmlToText } from "html-to-text";
import { Tool } from "langchain/tools";

export interface Headers {
 [key: string]: string;
}

export interface RequestTool {
 headers: Headers;
 maxOutputLength?: number;
 timeout: number;
}

export class HttpGetTool extends Tool implements RequestTool {
 name = "http_get";

 maxOutputLength = Infinity;

 timeout = 10000;

 constructor(
 public headers: Headers = {},
 { maxOutputLength }: { maxOutputLength?: number } = {},
 { timeout }: { timeout?: number } = {},
 ) {
 super(...arguments);

 this.maxOutputLength = maxOutputLength ?? this.maxOutputLength;
 this.timeout = timeout ?? this.timeout;
 }

 /** @ignore */
 async _call(input: string) {
 try {
 const res = await this.fetchWithTimeout(
 input,
 {
 headers: this.headers,
 },
 this.timeout,
 );
 let text = await res.text();
 text = htmlToText(text);
 text = text.slice(0, this.maxOutputLength);
 console.log(text);
 return text;
 } catch (error) {
 console.error(error);
 return (error as Error).toString();
 }
 }

 async fetchWithTimeout(
 resource: RequestInfo | URL,
 options = {},
 timeout: number = 30000,
 ) {
 const controller = new AbortController();
 const id = setTimeout(() => controller.abort(), timeout);
 const response = await fetch(resource, {
 ...options,
 signal: controller.signal,
 });
 clearTimeout(id);
 return response;
 }

 description = `A portal to the internet. Use this when you need to get specific content from a website.
 Input should be a url string (i.e. "https://www.google.com"). The output will be the text response of the GET request.`;
}