A Game-Changer: Claude Code Unveils Custom Sub-Agents for Advanced AI Workflows

For those who have been following this publication for some time, you know that hype, bandwagons, and rushing to publish articles on the day something is released are not the typical approach. However, that rule is being broken today to express sheer excitement for a new feature that was just announced.

The Dawn of Custom Sub-Agents

Claude Code is introducing a brand new feature: custom sub-agents. By using the /agent command, developers now get automatic switching and selection of agents running directly within Claude Code. This means Claude Code can now adopt any persona and do so automatically when needed. This capability has been a long-sought-after goal for inclusion in advanced agentic methods, making this announcement incredibly exciting. Work will now begin on updating installer scripts and methodologies to incorporate these new sub-agents, allowing for a streamlined setup process.

This could be a potential game-changer. While the term is often overused and cliché, the potential here is undeniable.

Building Your Own Agents

Many developers have created their own lightweight agent commands. Often, a full, heavyweight method isn't necessary. For instance, when simply taking notes, a quick agent to chat with—similar to custom GPTs—is ideal. A simple /agent command can be implemented by placing a file in a folder, giving it a name, and defining the agent's persona, purpose, and any necessary information.

If you've ever wondered how complex agentic methods are developed, the answer is to start by making your own agents. At their core, what are agents? They are stored prompts. If you have a particularly effective prompt or a specific way of working with an AI like Claude, you can save that prompt, put it in a file, and assign it a name and persona. With that, you have created your own custom agent for any task, not just coding. This principle is the foundation of many advanced agentic systems. The ability to now easily create and manage these within Claude Code is a significant step forward.

Previously, a lightweight agent framework might involve several files. You could type /agent followed by the name of an agent file, and it would load. These agents can be scoped to specific contexts. For example, within a large Obsidian notebook managed in VS Code, you might have folders for different projects or subjects. An agent could be an expert in one of those subjects, knowing about all the files in that folder and how to provide assistance on that topic. This has always worked well.

The Magic of Sub-Processes

The magic of what's arriving with the built-in /agent command is that these are all running in their own sub-processes. Let's explore the Claude Code documentation to understand the impact.

What are sub-agents? - They have a specific purpose and area of expertise. - They use their own dedicated context window. - They can be configured with specific tools, allowing precise control over their access to the file system, which has been a weaker point in some existing methods.

This is similar to features in platforms like Cursor, where you can define what an agent persona is and is not allowed to do. For example, a PM agent in Cursor can be configured to never modify code. In Claude, this was previously handled with text-based instructions in the agent file, which might not always be followed. Now, we can programmatically define what an agent is allowed to do, and Claude will enforce it. We can also include custom system prompts to guide its behavior, unlocking numerous new possibilities.

Key Benefits of the New Architecture

The official documentation lays out several key benefits:

• Context Preservation: Each sub-agent operates in its own context. This prevents pollution of the main conversation and keeps it focused on high-level objectives. This gives us the ability to have a true orchestrator running in a single chat instance while different agents perform their tasks.
• Specialized Expertise: If you have used any advanced agentic method, the value of this is immediately clear.
• Flexible Permissions: As mentioned, we can now scope different agents to only perform certain actions. This is a very exciting development.
• Reusability: Sub-agents can be used across different projects and shared with the team for consistent workflows. This is a huge one and will be an impactful change for any workflow that adopts this feature.

A New Workflow Paradigm

Imagine a typical developer cycle. The scrum master agent comes online, generates a user story, and then goes out of scope, freeing up context. The developer agent then comes in and begins working. If you're following Test-Driven Development (TDD), the QA agent could produce tests, then switch to the developer for implementation, cycling back and forth until the story is complete.

Once done, they both go out of context within the same window. Now, a senior QA agent can come in to review the code, refactor it, and ensure all acceptance criteria were met, adding a level of sophistication to ensure high-quality, clean code that adheres to the defined architecture. That agent then goes out of context, and the scrum master can return, pull information left as notes by the dev and QA agents, and prepare the next story. The cycle repeats.

Integrating any development method with these sub-agents will be incredibly powerful.

Beyond Software Development

This is about so much more than software development. Product managers and project managers can use it for planning roadmaps or creating big-picture visions. A clinical psychologist is using these concepts to assist with clinical psychology, which has nothing to do with software development. People are using the idea of creating small, specialized agents to help run their businesses and manage their lives. It's like using a chat AI but programming it with specific knowledge and understanding. This new feature provides a much better way to do it in Claude Code.

Getting Started

This is an exciting and unexpected development. For anyone using Claude Code, it is highly encouraged to check out the documentation and start experimenting with this new agent mode.

What's particularly cool is how easy it is to prototype a new agent. Simply type /agent and describe the agent you want, and it will generate the agent file for you. This is similar to auto-generating rules in Cursor or other IDEs. You can then go in and tweak the file, just as you would with rules in other systems. Create the rules, keep them simple, see what works, and then refine the file and try again.

After updating Claude Code, you will see a message with instructions on how to use this new feature. Have fun with this, and look for significant updates to community-driven agentic methods as we all work to incorporate this amazing system.