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Welcome to the crew

Crew is a combination of different agents with different set of skills. This is usefull when making big and capable systems. Since one agent can't do everything, the crew approach allows to distribure load across different agents.
Even if you are not building a complex system you can apply the crew approach to local models. Since they are quite limited they are not able to perform more than one or two tasks sucessfully.

The task

Lets take a simple task to get current internet speed using windows built-in ping tool.

Setup

We will setup mistral ollama model, but you can easily switch to any other model or provider. 

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using System.Diagnostics;
using System.Net;
using LangChain.Chains.StackableChains.Agents.Crew;
using LangChain.Chains.StackableChains.Agents.Crew.Tools;
using LangChain.Providers;
using LangChain.Providers.Ollama;
using Ollama;
using static LangChain.Chains.Chain;

var provider = new OllamaProvider(
    // url: "http://172.16.50.107:11434", // if you have ollama running on different computer/port. Default is "http://localhost:11434/api"
    );
var model = new OllamaChatModel(provider, id: "llama3.1").UseConsoleForDebug();

Making a tool

One of our agents would need to have access to windows ping tool. So let's build it! 

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var pingTool = new CrewAgentToolLambda("ping", "executes ping on specified ip address", address =>
{
    var addressParsed = IPAddress.Parse(address);
    var process = new Process
    {
        StartInfo = new ProcessStartInfo
        {
            FileName = "ping",
            Arguments = "-n 5 " + addressParsed,
            RedirectStandardOutput = true,
            UseShellExecute = false,
            CreateNoWindow = true
        }
    };
    process.Start();
    string result = process.StandardOutput.ReadToEnd();
    process.WaitForExit();
    return Task.FromResult(result);
});

Nothing special here. We just parse ip-address and executing ping command with it. Then we are taking the results and returning them as an answer.

Assembling the crew

We would need 2 agents:
- manager - every crew should have one. he is controlling and delegating tasks between agents
- pinger - our ping command specialist. He came here to chew bubble gum and ping servers, and he's all out of bubble gum.

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// controls agents
var manager = new CrewAgent(model, "manager", "assign task to one of your co-workers and return the result");

// the actual agent who does the job
var pinger = new CrewAgent(model, "pinger", "checks the speed of internet connection",
    "you using ping command and analyzing it's result. After this you print a single number as your final answer(the connection speed in milliseconds).");

Notice that we are giving a backstory to the pinger so he would understand his job better.

Now let's give a tool to out pinger. 

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pinger.AddTools(new[] { pingTool });

Now this tool is assigned to pinger and only he has access to it.

Building a chain

As always we are finishing by building a chain: 

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var chain =
    Set("What is my ping to google's main dns server?")
    | Crew(new[] { manager, pinger }, manager);

var res = await chain.RunAsync("text");
Console.WriteLine(res);

Crew chain requires a full list of agens(inluding manager) and manager agent specified separately.

Lets run and test it:

As the first step the task for manager is created asking a question:

What is my ping to google's main dns server?

As you may expect google's main dns server is a common knowladge, so manager aslo knows that it is 8.8.8.8.
Now he needs a way to ping it. But he can't do this by himself. So he asks the pinger to do his job: 

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...
Action: question
Action Input: pinger|What is the current ping time to Google's main DNS server (8.8.8.8)?
...
Now it's pinger's part. He sees that he has ping it his toolbelt so he can use it: 
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...
Action: ping
Action Input: 8.8.8.8
...
Final Answer: The average ping time to Google's main DNS server (8.8.8.8) is 17 milliseconds.

Now manager receives the answer and makes the final conclusion: 

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...
Observation: The average ping time to Google's main DNS server (8.8.8.8) is 17 milliseconds.
Thought: Do I need to use a tool? No
Final Answer: The current ping time to Google's main DNS server is 17 milliseconds.

Complete code

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using System.Diagnostics;
using System.Net;
using LangChain.Chains.StackableChains.Agents.Crew;
using LangChain.Chains.StackableChains.Agents.Crew.Tools;
using LangChain.Providers;
using LangChain.Providers.Ollama;
using Ollama;
using static LangChain.Chains.Chain;

var provider = new OllamaProvider(
    // url: "http://172.16.50.107:11434", // if you have ollama running on different computer/port. Default is "http://localhost:11434/api"
    );
var model = new OllamaChatModel(provider, id: "llama3.1").UseConsoleForDebug();


var pingTool = new CrewAgentToolLambda("ping", "executes ping on specified ip address", address =>
{
    var addressParsed = IPAddress.Parse(address);
    var process = new Process
    {
        StartInfo = new ProcessStartInfo
        {
            FileName = "ping",
            Arguments = "-n 5 " + addressParsed,
            RedirectStandardOutput = true,
            UseShellExecute = false,
            CreateNoWindow = true
        }
    };
    process.Start();
    string result = process.StandardOutput.ReadToEnd();
    process.WaitForExit();
    return Task.FromResult(result);
});


// controls agents
var manager = new CrewAgent(model, "manager", "assign task to one of your co-workers and return the result");

// the actual agent who does the job
var pinger = new CrewAgent(model, "pinger", "checks the speed of internet connection",
    "you using ping command and analyzing it's result. After this you print a single number as your final answer(the connection speed in milliseconds).");


pinger.AddTools(new[] { pingTool });


var chain =
    Set("What is my ping to google's main dns server?")
    | Crew(new[] { manager, pinger }, manager);

var res = await chain.RunAsync("text");
Console.WriteLine(res);