AgentWorkflow doesn't call functions when using Ollama

[ohchi]

I change the example https://developers.llamaindex.ai/typescript/framework/modules/agents/agent_workflow/#single-agent-workflow to work with local LLM by @llamaindex/ollama adapter package:

import { tool } from 'llamaindex';
import { agent } from '@llamaindex/workflow';
import { ollama } from '@llamaindex/ollama';

(async () => {
  // Define a joke-telling tool
  const jokeTool = tool(() => 'Baby Llama is called cria', {
    name: 'joke',
    description: 'Use this tool to get a joke',
  });

  // Create an single agent workflow with the tool
  const jokeAgent = agent({
    tools: [jokeTool],
    llm: ollama({ model: 'qwen2.5-coder:14b' }),
  });

  // Run the workflow
  const result = await jokeAgent.run('Tell me something funny');
  console.log(result.data.result); // Baby Llama is called cria
  console.log('---------------------');
  console.log(result.data.message); // { role: 'assistant', content: 'Baby Llama is called cria' }
})().catch(console.error);

The output is:

{
  "name": "joke",
  "arguments": {}
}
---------------------
{
  role: 'assistant',
  content: '{\n  "name": "joke",\n  "arguments": {}\n}'
}

I'm new in the framework, but it looks like this is similar to run-llama/llama_index#17713
Could someone clarify it for me?