Custom agents in Microsoft/skills codebase.

In this article, we review custom agents in Microsoft/skills repository. You will learn:

1. What are custom agents?

2. github/agents in Microsoft skills repo.

What are custom agents?

Custom agents enable you to configure the AI to adopt different personas tailored to specific development roles and tasks. For example, you might create agents for a security reviewer, planner, solution architect, or other specialized roles. Each persona can have its own behavior, available tools, and instructions.

You can also use handoffs to create guided workflows between agents. Transition seamlessly from one specialized agent to another with a single select. For example, move from a planning agent directly into an implementation agent, or hand off to a code reviewer with the relevant context.

I picked the above info from the Custom Agents VS Code docs.. Learn more about how you can Create Custom agents..

Below is a planning agent example provided in the docs:

---
description: Generate an implementation plan for new features or refactoring existing code.
name: Planner
tools: ['web/fetch', 'search/codebase', 'search/usages']
model: ['Claude Opus 4.5', 'GPT-5.2']  # Tries models in order
handoffs:
  - label: Implement Plan
    agent: agent
    prompt: Implement the plan outlined above.
    send: false
---
### Planning instructions
You are in planning mode. Your task is to generate an implementation plan for a new feature or for refactoring existing code.
Don't make any code edits, just generate a plan.
 
The plan consists of a Markdown document that describes the implementation plan, including the following sections:
 
* Overview: A brief description of the feature or refactoring task.
* Requirements: A list of requirements for the feature or refactoring task.
* Implementation Steps: A detailed list of steps to implement the feature or refactoring task.
* Testing: A list of tests that need to be implemented to verify the feature or refactoring task.

There is a section about how the custom agent file should be structured, Check it out.

I wanted to provide references to custom agents in the OSS repos and I found Microsoft/skills.

Microsoft/skills

Skills repo in Microsoft org provides Skills, MCP servers, Custom Agents, Agents.md for SDKs to ground Coding Agents.

.github/agents in Microsoft skills repo.

I found the following agents defined in the Microsoft/skills repo..

backend.agent.md
frontend.agent.md
infrastructure.agent.md
planner.agent.md
presenter.agent.md
scaffolder.agent.md

frontend.agent.md

In the frontend.agent.md,. below is the structure defined:

---
name: Frontend Developer
description: React/TypeScript specialist for CoreAI DIY frontend development with React Flow, Zustand, and Tailwind CSS
tools: ["read", "edit", "search", "execute"]
---

And has the above table of contents.

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References:

1. microsoft/skills/.github/agents.

2. code.visualstudio.com/docs/copilot/customization/custom-agents.