neo4j as a custom tool

[ernesttan1976]

import { Neo4jGraph } from "@langchain/community/graphs/neo4j_graph";
import { OpenAI } from "@langchain/openai";
import { GraphCypherQAChain } from "langchain/chains/graph_qa/cypher";

/**

• This example uses Neo4j database, which is native graph database.
• To set it up follow the instructions on https://neo4j.com/docs/operations-manual/current/installation/.
  */

const url = "neo4j://localhost:7687";
const username = "neo4j";
const password = "password";

const graph = await Neo4jGraph.initialize({ url, username, password });
const model = new OpenAI({ temperature: 0 });

const chain = GraphCypherQAChain.fromLLM({
llm: model,
graph,
});

const res = await chain.run($query);
console.log(res);
return res

I added this tool with the above JS code. But it is not calling the function at all. Please advise? Thank you.