Preface¶

When taking over an unfamiliar repository, the most time-consuming task is rarely writing code, but first figuring out: what framework does the project use, where is the data stored, how are interfaces exposed, which path does the login authentication follow, how to run it locally, and how to deploy it online. The README might be outdated, verbal handovers are prone to omissions, and when stepping in as an on-call engineer, you can only search and guess as you go.

Agent Skills is a portable instruction package that uses SKILL.md to teach domain workflows to AI Agents. codebase-onboarding is specifically designed for the scenario of “quickly understanding an unfamiliar codebase”: it spins up multiple read-only explore sub-agents in parallel to investigate architecture, data models, APIs, authentication and deployment, then synthesizes a actionable onboarding document.

What is this¶

codebase-onboarding is included in the resources/codebase-onboarding/ directory of the spencerpauly/awesome-cursor-skills repository, categorized under the Cursor-Native skills list. Its official one-sentence positioning is:

Launch multiple explore subagents in parallel to investigate architecture, data models, auth, APIs, and deployment. Synthesize into an onboarding document.

That is to say, it does not require you to write the architecture description manually, but specifies that the Agent should follow a fixed workflow: “parallel exploration → summarization → write ONBOARDING.md”. The skill file itself follows the universal SKILL.md format; it will be automatically detected in Cursor, or you can manually call it via / in a conversation. There are different implementations of similar names in other repositories, this article only introduces the original version from spencerpauly.

Core Workflow and Capabilities¶

The official SKILL.md splits the process into three steps.

1. Launch 5 explore sub-agents in parallel¶

Each sub-agent only takes charge of one area, with the prompt hardcoded in the skill, and clear boundaries of responsibility:

The explore sub-agents are read-only, focused on search and reading, suitable for large-scale investigation without modifying code. The skill tip notes: the entire process is usually fast; for monorepos, you can add additional exploration agents per app/package.

2. Summarize into a structured onboarding document¶

The five results need to be combined into one document, with a roughly following template (commands and paths filled in based on the investigation results):

# Codebase Onboarding

## Quick Start
1. Clone the repo
2. Install dependencies: `<command>`
3. Set up environment: copy `.env.example` to `.env`
4. Run database migrations: `<command>`
5. Start dev server: `<command>`

## Architecture
...

## Data Models
...

## API Reference
...

## Authentication
...

## Deployment
...

## Key Files to Know
- `<file>` — <why it matters>

The skill also requires the document to have “perspective”: highlight the files that should be viewed first, instead of pasting the entire directory tree; and include common pitfalls — easy-to-miss environment variables, system dependencies, installation traps, etc.

3. Save to disk¶

By default, it is written to ONBOARDING.md in the project root directory; if you specify another path, it will be saved to the specified location. This way, new hires, on-duty colleagues and subsequent Agent sessions can directly reference the same material.

Installation and Activation¶

Method 1: Manually place the skill directory (recommended by the repository README)¶

The instructions for awesome-cursor-skills state: copy the existing SKILL.md into .cursor/skills/, and the Agent will automatically detect it. For this skill, you can organize it as:

mkdir -p .cursor/skills/codebase-onboarding
# Download or copy SKILL.md to this directory from the repository
# Source file:
# https://github.com/spencerpauly/awesome-cursor-skills/blob/main/resources/codebase-onboarding/SKILL.md

The directory structure should look similar to:

.cursor/
└── skills/
    └── codebase-onboarding/
        └── SKILL.md

According to the Cursor Skills documentation, skills will also be loaded from these locations:

To be compatible with other tools, Cursor also loads .claude/skills/, .codex/skills/ and their corresponding user directories. The name must match the folder name; the frontmatter of this skill has name set to codebase-onboarding and user-invocable: true, making it suitable for explicit calls in conversations.

Method 2: Install with npx skills¶

vercel-labs/skills provides a cross-Agent skill installation CLI. According to the parameter conventions of this CLI, you can install from this repository by name:

npx skills add spencerpauly/awesome-cursor-skills --skill codebase-onboarding

If you need to install to a specific Agent, add -a (e.g. cursor, claude-code, codex); add -g to install to the user directory. The specific target directory depends on the current version of the CLI.

Method 3: Import from GitHub in Cursor¶

The official documentation also supports: open the sidebar Customize → Rules → Add Rule → select Remote Rule (Github), and fill in the repository address to import. Suitable for scenarios where you don’t want to manually copy files.

Typical Usage¶

After installation, type / in the Agent conversation, search and select codebase-onboarding, or directly state your intent, for example:

/codebase-onboarding
Please follow the skill workflow to conduct parallel investigation of this repository and generate ONBOARDING.md.

You can also specify the output location:

Help me do codebase onboarding, write the result to docs/ONBOARDING.md,
and highlight the files new hires should view on their first day in the Key Files section.

If the repository is a monorepo, you can add constraints according to the official tip:

This is a turbo monorepo. In addition to the default 5-way investigation,
please add one more explore for apps/web and packages/api each, then synthesize into one document.

The Agent should execute according to the skill: spawn five types of explore agents in parallel → synthesize according to the template → write to ONBOARDING.md. After generation, it is recommended to manually check whether the Quick Start commands and environment variables match the actual scripts, then commit to the repository for team reuse.

Applicable Scenarios and Notes¶

These situations are suitable:
- New hires joining the team or cross-team support, needing a map that allows them to “run the project and know where to make changes”
- On-call / temporary takeover, quickly building a mental model of architecture, authentication and deployment
- The repository lacks effective onboarding documentation, or the README is out of sync with the current state, and you need to re-summarize from the code
- You want to固化 the investigation results into ONBOARDING.md to reduce repeated verbal explanations

Please note when using:
1. Depends on Cursor’s parallel explore capability. This skill is listed under the Cursor-Native category, with the core being spinning up multiple explore sub-agents simultaneously; in other environments that only support general SKILL.md but do not have similar sub-agent orchestration capabilities, the effect may be compromised and adjustments need to be made according to the actual tool capabilities.
2. The output needs to be verified. Automatic summarization may miss niche scripts, private deployment details or uncommitted operation and maintenance conventions; key startup commands, key sources, and permission models should be confirmed manually.
3. The document should be selective. The official requirement is to highlight the “start here” files and gotchas, instead of listing everything without discrimination; after generation, you can delete redundancies and add business context.
4. Do not mix up skills with the same name. Other author repositories also have skills named codebase-onboarding, and the workflow and output (for example, whether to generate CLAUDE.md) may be different; when installing, make sure to pick the one from spencerpauly/awesome-cursor-skills.

Summary¶

codebase-onboarding固化s “figuring out an unfamiliar repository” into a reusable Agent workflow: five parallel explorations of architecture, data, APIs, authentication and deployment, then synthesizes a commit-ready ONBOARDING.md. It is very practical for new hires to get started and temporary takeovers. The source code and instructions can be found at:

https://github.com/spencerpauly/awesome-cursor-skills/tree/main/resources/codebase-onboarding

The general instructions for Agent Skills can be found at:

https://cursor.com/docs/skills