Build Smarter AI Applications with AWS Bedrock Multi-Agent Collaboration

Hey 👋🏽

this newsletter is about 🥁 AI 🤖

We haven't talked too much about AI, Bedrock, MCPs, and agents yet - so we want to change that.

Please let us know if this it interests you to build AI on AWS, or if you are much more interested on hands-on fundamentals services.

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Now, let's dive into the world of AI Agents 🤖

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Multi-AI Agents with Bedrock

As always, this newsletter comes not just with text but also with code. Here is the GitHub repository containing all the code to deploy

• Bedrock agents
• Next.js frontend

... in your own AWS Account!

bedrock-multi-agent-collaboration

🤖 A Simple Multi-Agent Bedrock Application with SST

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lambda bedrock sst

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Introduction

AI agents are very good at doing exactly one thing.

They are not very good at solving complex problems if they cover different domains.

This is where multi-agent systems come in. With multi-agent systems, we can combine the strengths of multiple agents to solve complex problems. Each agent is responsible for a specific task, and they work together to solve a larger problem. This way, we can use the strengths of each agent to solve a multi-step problem that would be challenging for a single agent to accomplish alone.

In this article, we’ll explore how we can use Amazon Bedrock to create sophisticated multi-agent collaborations.

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Our App

In this application, we build a story writer. This story writer consists of three different agents:

1. Plot Creator
2. Writer
3. Story Creator

The application is fully serverless - meaning only usage-based processing and close-to-zero costs.

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What is Amazon Bedrock?

Amazon Bedrock is a fully managed service that allows us to build and scale generative AI applications. It provides a wide range of pre-trained models from Amazon, including models for natural language processing, computer vision, and more.

It also allows you to access models from other well-known providers.

Key Features and Capabilities

One great advantage of Bedrock is that it abstracts the underlying infrastructure and underlying models. This allows us to:

• Easily switch between different models
• Choose different infrastructure providers

All of that is handled automatically!

You can access models from different providers. All the billing is centralized within AWS.

Understanding Multi-Agent Systems

Multi-agent systems are systems that consist of multiple agents. Each agent focuses on a specific task while being specialized in that task.

This works very well for complex tasks that require a combination of different skills.

The multi-agent system is able to solve the task at hand by combining the results of the individual agents. The supervisor agent supervises all agents.

Benefits of Multi-Agent Collaboration

Agents are very good at doing one thing. They work best if they are carefully crafted for a single domain.

Each single agent is responsible for exactly one task. Compared to one huge agent this allows us to

• get faster responses
• use less computational overhead
• make better decisions, since the one agent is only specialised in its domain

Building Our Own Multi-Agent System

Now, let's build! We are building a story writer consisting of three different parts:

1. Supervisor Creator
2. Sub-Agent: Plot Creator
3. Sub-Agent: Writer

Setting Up the Project

For setting up the project, we’re going to use SST v3. Let’s start by creating a new SST project.

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npx create-sst@latest bedrock-multi-agent-collaboration
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This will create a new SST project with a basic structure.

We use Next.js as our frontend, simply to demonstrate the capability of our implementation.

Defining Our Infrastructure

What do we need for our multi-agent system?

There are a few different components and services we’ll need:

• A role that our agents can assume and use to make requests to the models provided through Bedrock.
• Multiple agents can be used to solve different parts of a task.
• A way to coordinate the agents and combine their results: a supervisor agent.

Let’s start by defining the role that our agents will assume. With SST, this is super simple and can be quickly set up.

We can use the already existing AWS-managed policy AmazonBedrockFullAccess to grant the necessary permissions. In a real-world scenario, you might want to create a custom policy to grant only the necessary permissions.

Next, we need to define our agents!

Let’s quickly discuss which agents we need and which role they will have in our scenario!

1. Plot Creator: This agent is responsible for creating a plot for a story. It specializes in creating structured outlines.
2. Writer: This agent is responsible for writing a story. Its role is to transform structured plots into well-written stories.
3. Story Creator: This agent is the supervisor. Its role is to coordinate the other agents and combine their results.

For creating an agent, we have a few required options that we need to set:

• agentResourceRoleArn: The role that the agent will assume to make requests to the models.
• foundationModel: The model that will be used to actually run our prompts.
• instruction: The instruction that will be used as a base for the agent.
• agentCollaboration: The collaboration mode that will be used by the agent. It can be either SUPERVISOR, COLLABORATOR or it can be undefined. When nothing is provided, the agent will be a standalone agent.

So what do we need to do?

• We need to create the collaborators Plot Creator and Writer. They need to be assigned their specific roles via the system prompts.
• We need to create a supervisor Story Creator that will be responsible for coordinating the other agents. This one will be the one that will be invoked by the user.
• We need to create the agent collaborator assignments for the Story Creator to use the collaborators. These also need prompts so that the supervisor knows when and how to use the collaborators.

That’s basically it!

For creating the two collaborator agents, we’ll use the aws.bedrock.AgentAgent resource from Pulumi that is provided by SST. We need to make sure to assign them our previously created role, the model we want to use, the system prompt and the collaborator mode (COLLABORATOR).

Let’s have a look at an example for the Plot Creator agent:

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You’ll find the details of the Writer and Story Creator agent in the GitHub repository.

Now, we’ve created our agents, including the supervisor. For both of our collaborators, we also need to define an alias. An alias is a specific version of an agent that can be used to invoke the agent.

Let’s have a look at how we define the alias for the Plot Creator agent:

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With an alias, we can create different versions of the same agent, e.g,. with different prompts or different models.

Next, we need to assign the collaborators to our supervisor agent.

This is done by having a aws.bedrock.AgentAgentCollaborator resource. This resource will be used to assign the collaborators to the supervisor.

Let’s have a look at how we set up the Story Creator agent to use the Plot Creator:

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This will assign the Plot Creator agent to the Story Creator agent as a collaborator. We’ve also told the story creator how and when to invoke the plot creator.

We’re also telling the story creator to relay the conversation history to the plot creator. This way, the order of the conversation is preserved.

The last step of the process is to create an alias for our supervisor agent so we can invoke it later on.

Which Models are Available in Bedrock?

A question that might arise is:

We can get them via the Bedrock web console. Just visit the Model catalog section and search for the model you’re interested in.

When clicking on a model, you’ll see the model details and the model ID in the table.

A Simple Frontend

This step is not really relevant for the multi-agent system, but it’s a good way to test our agents.

Let’s create a simple frontend to submit prompts to our agents. Also, as the submission can take a while to complete, we’ll store the results in a DynamoDB table.

This is done by having a Lambda-based API that will be invoked by the frontend. The API Lambda function will invoke another function asynchronously that will invoke the Story Creator agent.

This way, we can keep the frontend simple and the user experience responsive. As long as there’s no result in the DynamoDB table, the frontend will show a loading spinner.

Testing our Multi-Agent System

Now that we’ve set up our agents, let’s test them! To see their actual behavior, we’re going to use the web console of Bedrock to invoke our Story Creator agent.

Let’s go to the Agents section in the Bedrock console and select our story-creator agent. By clicking on Test on the top left, we can now invoke our agent.

As a simple test prompt, we can use the following (you’re free to use any other prompt):

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The story has to be about a cat that always dreams about flying.
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By clicking on Run, we’re submitting the prompt to our agent.

After a few seconds, we’ll see the results. They should look like this when clicking on the Show trace button:

As we can see, our Story Creator is coordinating the other agents to create a story about a cat that always dreams about flying. It first creates a plot by using the Plot Creator agent. Then, it uses the Writer agent to write a story based on the plot.

At the end, the Story Creator combines the results of the other agents to return us the final story.

When looking at the trace, we can also scroll down to see the actual messages exchanged between the agents.

We can also see the wrapped prompts that were used to invoke the agents. This includes the details about the available agents and the functions that the supervisor can use to coordinate and call the other agents.

Let’s take a look at this wrapped prompt:

We can see that the supervisor gets the information about the available agents and how to invoke them.

Possible Issues Along the Way

While implementing this, we ran into a few issues. Let’s go over them and how we solved them.

Throttling Exceptions

You might face the following error:

This is due to the fact that the default quotas for the on-demand models are very low. To resolve this, you need to create a basic support ticket (not a service quota limit increase, as the on-demand models are not part of the service quota increase).

Bedrock Models are not available in all regions

Not all Bedrock models are available in all regions. This means you need to check which models are available in the region you’re interested in. In our example project, we’re using the latest Anthropic models and the us-east-1 region.

Supervisor Agent Is Not Invoking the Other Agents

This was not related to a technical issue with Bedrock but a prompting issue. The prompt of the supervisor agent, as well as the prompts on how to invoke the other agents, needs to be carefully crafted.

This means, it needs to be very clear for the model what the role of the supervisor is. It needs to know which agents are available and when to invoke them.

This means there can’t be any ambiguity in the prompt. Otherwise, the supervisor agent tends not to invoke the other agents but tries to solve the task on its own.

Let’s compare a good and a bad prompt for our supervisor agent:

Bad prompt:

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You are a Plot Creator specializing in creating structured story outlines.

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Given a genre and a premise, generate a well-structured plot, including:

Good prompt:

Why is the second prompt better?

The first prompt is very specific and tells the model exactly what to do. However, it also includes a lot of instructions that are not necessary for the model to understand the task.

The second prompt is more general and tells the model what the task is. It also includes instructions on how and when to invoke the other agents.

This way, the model knows exactly what to do and can delegate the work to the other agents.

Best Practices and Considerations

While multi-agent systems are powerful, they come with their own set of challenges. They go beyond the scope of this article, but we’ll cover some of the most important ones.

What are the challenges and limitations of multi-agent systems?

• 💸 Cost Management: Each agent interaction counts as a separate API call, which can quickly add up in costs. Monitor your usage carefully and set up appropriate budget alarms. Remember that the supervisor is able to invoke the other agents multiple times. This means, you should be really careful about how you design your prompts.
• ⚡️ Latency: Multiple agent interactions mean longer response times. Consider this in your application design and set appropriate user expectations. If you design something for a real-time use case, a multi-agent approach might not be the best fit.
• 🐛 Error Handling: With multiple agents, error handling becomes more complex. On each individual step, there’s a chance that something goes wrong. This means, you need to have a plan on how to handle these errors. The tracing in the web console can help you to carefully test your prompts.
• 🔐 Agent Boundaries: Each agent should have a clearly defined boundary. This means, it needs to be clear for the model what the role of the agent is. It should know which models it can use and which it can’t. This also includes the data that it can access.
• 🔒 Data Privacy: Be mindful of the data you’re sending to the models. Consider implementing data anonymization or masking where appropriate. Especially when you’re using the models for sensitive data within strictly regulated locations, like the European Union, you need to be careful about the data you’re sending.

Conclusion

Multi-agent systems are a great way to solve complex problems. They allow us to combine the strengths of multiple agents to solve complex tasks.

With Bedrock, we can easily create multi-agent systems and invoke them with ease. We can also use multiple, different models for different agents. This way, we can use the best model for the specific task at hand.

Invoke this agent with a genre and premise to receive a structured plot. Use the result to inform the next step (story writing). Invoke this agent with a structured plot. It will return a full story based on that outline.

That's it!

Thanks for reading this newsletter. Are you already using Bedrock a lot in your day-to-day work?

Let us know what you think!

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​Tobias Schmidt & Sandro Volpicella & from AWS Fundamentals​
​Cloud Engineers • Fullstack Developers • Educators

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