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Three-Agent Collaboration, with message Routing

Script in langroid-examples

A full working example for the material in this section is in the script in the langroid-examples repo: examples/quick-start/

Let's change the number game from the three agent chat example slightly. In that example, when the even_agent's LLM receives an odd number, it responds with DO-NOT-KNOW, and similarly for the odd_agent when it receives an even number. The step() method of the repeater_task considers DO-NOT-KNOW to be an invalid response and continues to look for a valid response from any remaining sub-tasks. Thus there was no need for the processor_agent to specify who should handle the current number.

But what if there is a scenario where the even_agent and odd_agent might return a legit but "wrong" answer? In this section we add this twist -- when the even_agent receives an odd number, it responds with -10, and similarly for the odd_agent when it receives an even number. We tell the processor_agent to avoid getting a negative number.

The goal we have set for the processor_agent implies that it must specify the intended recipient of the number it is sending. We can enforce this using a special Langroid Tool, RecipientTool. So when setting up the processor_task we include instructions to use this tool (whose name is recipient_message, the value of RecipientTool.request):

processor_agent = lr.ChatAgent(config)
processor_task = lr.Task(
    name = "Processor",
        You will receive a list of numbers from me (the user).
        Your goal is to apply a transformation to each number.
        However you do not know how to do this transformation.
        You can take the help of two people to perform the 
        If the number is even, send it to EvenHandler,
        and if it is odd, send it to OddHandler.

        IMPORTANT: send the numbers ONE AT A TIME

        The handlers will transform the number and give you a new number.        
        If you send it to the wrong person, you will receive a negative value.
        Your aim is to never get a negative number, so you must 
        clearly specify who you are sending the number to, using the
        `recipient_message` tool/function-call, where the `content` field
        is the number you want to send, and the `recipient` field is the name
        of the intended recipient, either "EvenHandler" or "OddHandler".        

        Once all numbers in the given list have been transformed, 
        say DONE and show me the result. 
        Start by asking me for the list of numbers.

To enable the processor_agent to use this tool, we must enable it:


The rest of the code remains the same as in the previous section, i.e., we simply add the two handler tasks as sub-tasks of the processor_task, like this:

processor_task.add_sub_task([even_task, odd_task])

One of the benefits of using the RecipientTool is that it contains mechanisms to remind the LLM to specify a recipient for its message, when it forgets to do so (this does happen once in a while, even with GPT-4).

Feel free to try the working example script in the langroid-examples repo: examples/quick-start/

python3 examples/quick-start/

Below is screenshot of what this might look like, using the OpenAI function-calling mechanism with the recipient_message tool:


And here is what it looks like using Langroid's built-in tools mechanism (use the -t option when running the script):


And here is what it looks like using

Next steps

In the next section you will learn how to use Langroid with external documents.