How to sequentially call tools with LangGraph?

[exil0867]

I have a ReAct agent and I'm struggling to get it to call tools in a sequential way.

Here is my issue:

I have a tool responsible for scheduling appointments, it expects appointmentDate argument, however, without triggering the get_current_date tool, it never gets the date right because the appointment date will be based on the LLMs outdated date. Passing the date tool is not enough, it will be a hit or miss, sometimes it forgets to call it before the appointment tool.

I've been trying to force date call right before the appointment call and I've had no luck.

This is how my workflow looks:

const routeMessage = (state) => {
  const { messages } = state;
  const lastMessage = messages[messages.length - 1];
  // If there's no tool call, simply route to END.
  if (!lastMessage?.tool_calls?.length) {
    return END;
  }

  // Route to tool call
  return "tools";
};

const workflow = new StateGraph(MessagesAnnotation)
      .addNode('agent', callModel)
      .addEdge(START, 'agent')
      .addNode('tools', this.toolNode)
      .addEdge('tools', 'agent')
      .addConditionalEdges('agent', routeMessage)

How can I make it work this way:

1. I show the intent of making an appointment, for example, I say "next Monday at 1PM".
2. The agent realizes it should schedule an appointment
3. it calls the get_current_date tool
4. it then calls the scheduleAppointment tool where it's appointmentDate argument will be the next Monday from the current date.

Is there any way to achieve this? I know that probably needs an additional node where appointment calls are routed to it, but i can't figure out how to write it.

I also have no idea why embedding the current date in the initial system prompt does not work. The LLM would still use it's own outdated date.

[dosubot[bot]]

Hey @exil0867! I'm here to help you with any bugs, questions, or contributions you have. Let's tackle this issue together!

To ensure that the get_current_date tool is called before the scheduleAppointment tool in your LangGraph workflow, you can add specific nodes for each tool and set up conditional edges to enforce the sequence. Here's how you can achieve this:

1. Define the Nodes: Create functions for get_current_date and scheduleAppointment, and add them as nodes to the StateGraph.

2. Set Conditional Edges: Use add_conditional_edges to ensure that get_current_date is called before scheduleAppointment.

Here's an example of how you can structure your workflow:

// Define the function for getting the current date
function getCurrentDate(state) {
  // Logic to get the current date
  const currentDate = new Date().toISOString().split('T')[0]; // Example date
  state.messages.push({ content: `Current date is ${currentDate}` });
  return state;
}

// Define the function for scheduling an appointment
function scheduleAppointment(state) {
  // Logic to schedule an appointment
  state.messages.push({ content: "Appointment scheduled" });
  return state;
}

// Create the workflow
const workflow = new StateGraph(MessagesAnnotation)
  .addNode('agent', callModel)
  .addEdge(START, 'agent')
  .addNode('tools', this.toolNode)
  .addEdge('tools', 'agent')
  .addNode('get_date', getCurrentDate)
  .addNode('schedule', scheduleAppointment)
  .addConditionalEdges('agent', routeMessage)
  .addConditionalEdges('get_date', (state) => 'continue', { 'continue': 'schedule' })
  .addConditionalEdges('schedule', (state) => 'end', { 'end': END });

// Modify the routeMessage function to handle the new sequence
function routeMessage(state) {
  const { messages } = state;
  const lastMessage = messages[messages.length - 1];
  if (!lastMessage?.tool_calls?.length) {
    return END;
  }
  if (lastMessage.tool_calls.includes('scheduleAppointment')) {
    return 'get_date';
  }
  return 'tools';
}

This setup ensures that when the agent decides to schedule an appointment, it first routes to the get_date node to fetch the current date, and then proceeds to the schedule node to schedule the appointment with the correct date.

Regarding embedding the current date in the initial system prompt, it might not work as expected because the LLM may not consistently use the provided date over its internal knowledge. Using a structured workflow as shown above ensures the correct sequence of tool calls.

To continue talking to Dosu, mention @dosu.

---

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[exil0867]

Hey @exil0867! I'm here to help you with any bugs, questions, or contributions you have. Let's tackle this issue together!

To ensure that the get_current_date tool is called before the scheduleAppointment tool in your LangGraph workflow, you can add specific nodes for each tool and set up conditional edges to enforce the sequence. Here's how you can achieve this:

1. **Define the Nodes**: Create functions for `get_current_date` and `scheduleAppointment`, and add them as nodes to the `StateGraph`.

2. **Set Conditional Edges**: Use `add_conditional_edges` to ensure that `get_current_date` is called before `scheduleAppointment`.

Here's an example of how you can structure your workflow:

// Define the function for getting the current date
function getCurrentDate(state) {
  // Logic to get the current date
  const currentDate = new Date().toISOString().split('T')[0]; // Example date
  state.messages.push({ content: `Current date is ${currentDate}` });
  return state;
}

// Define the function for scheduling an appointment
function scheduleAppointment(state) {
  // Logic to schedule an appointment
  state.messages.push({ content: "Appointment scheduled" });
  return state;
}

// Create the workflow
const workflow = new StateGraph(MessagesAnnotation)
  .addNode('agent', callModel)
  .addEdge(START, 'agent')
  .addNode('tools', this.toolNode)
  .addEdge('tools', 'agent')
  .addNode('get_date', getCurrentDate)
  .addNode('schedule', scheduleAppointment)
  .addConditionalEdges('agent', routeMessage)
  .addConditionalEdges('get_date', (state) => 'continue', { 'continue': 'schedule' })
  .addConditionalEdges('schedule', (state) => 'end', { 'end': END });

// Modify the routeMessage function to handle the new sequence
function routeMessage(state) {
  const { messages } = state;
  const lastMessage = messages[messages.length - 1];
  if (!lastMessage?.tool_calls?.length) {
    return END;
  }
  if (lastMessage.tool_calls.includes('scheduleAppointment')) {
    return 'get_date';
  }
  return 'tools';
}

It still provides scheduleAppointment with an outdated date...

[exil0867]

It still provides scheduleAppointment with an outdated date...