ReAct agent crashes when no tool needed

[alexander-fischer]

I use the ReActAgent together with Llama3 via Ollama. If I ask a normal question like "Hello. How are you?" the agent crashes, since it's searching for a tool to use. I guess it should not throw an error if no tool needs to be used. Here is the stack trace:

Starting step(id, 0cf7f648-3c0c-4651-90a2-e3713085e94d).
Enqueueing output for step(id, 0cf7f648-3c0c-4651-90a2-e3713085e94d).
/Users/alex/dev/research/llamaindex-ts/node_modules/llamaindex/dist/cjs/agent/react.js:63
        throw new Error(`Could not extract tool use from input text: "${inputText}"`);
              ^
Error: Could not extract tool use from input text: "I need to use a tool to help me answer the question.

Action: None
Action Input: None

Please let me know how I can assist you with your task or question."
    at extractToolUse (/Users/alex/dev/research/llamaindex-ts/node_modules/llamaindex/dist/cjs/agent/react.js:63:15)
    at reACTOutputParser (/Users/alex/dev/research/llamaindex-ts/node_modules/llamaindex/dist/cjs/agent/react.js:176:54)
    at taskHandler (/Users/alex/dev/research/llamaindex-ts/node_modules/llamaindex/dist/cjs/agent/react.js:283:30)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Object.pull (/Users/alex/dev/research/llamaindex-ts/node_modules/llamaindex/dist/cjs/agent/base.js:432:13)

Here is the code for reproducing:

import { FunctionTool, Ollama, ReActAgent } from "llamaindex"

function add({ a, b }: { a: number; b: number }) {
  return `${a + b}`
}

const sumJSON = {
  type: "object",
  properties: {
    a: {
      type: "number",
      description: "The first number",
    },
    b: {
      type: "number",
      description: "The second number",
    },
  },
  required: ["a", "b"],
} as const

const sumTool = new FunctionTool(add, {
  name: "sumTool",
  description: "Add two integers and returns the result integer",
  parameters: sumJSON,
})

function multiply({ a, b }: { a: number; b: number }) {
  return `${a * b}`
}

const multiplyJSON = {
  type: "object",
  properties: {
    a: {
      type: "number",
      description: "The first number",
    },
    b: {
      type: "number",
      description: "The second number",
    },
  },
  required: ["a", "b"],
} as const

const multiplyTool = new FunctionTool(multiply, {
  name: "multiplyTool",
  description: "Multiply two integers and returns the result integer",
  parameters: multiplyJSON,
})

async function main() {
  const context = `You're an agent that function as a calculator. 
  Use the tools only if you're asked to calculate something.
  Don't provide more information than it was asked for.
  Do not rely on prior knowledge.`

  const ollama = new Ollama({
    model: "llama3",
  })

  const agent = new ReActAgent({
    llm: ollama,
    tools: [sumTool, multiplyTool],
    systemPrompt: context,
    verbose: true,
  })

  const prompt = "Hello. How are you?"

  const { response } = await agent.chat({
    message: prompt,
    verbose: true,
  })
  console.log("ANSWER:", response.message.content)
}

void main().then(() => {
  console.log("Done")
})