> ## Documentation Index
> Fetch the complete documentation index at: https://aisa.one/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Pre-Built Skills vs Custom Skills — When to Use Each

> Understand when to install a pre-built Agent Skill from the agent-skills registry versus creating your own SKILL.md from scratch with aisa skills init.

There are two ways to give your AI coding agent new capabilities with AIsa Agent Skills: install a pre-built skill from the [agent-skills](https://github.com/AIsa-skills) registry, or write your own `SKILL.md` from scratch. The right choice depends on whether your use case is already covered.

***

## The core difference

|                    | **Pre-built skill** (from registry)                                 | **Custom skill** (your own SKILL.md)  |
| ------------------ | ------------------------------------------------------------------- | ------------------------------------- |
| **Source**         | [AIsa-team/agent-skills](https://github.com/AIsa-team/agent-skills) | You write it                          |
| **How to install** | `aisa skills install <slug>`                                        | `aisa skills init <name>` + edit      |
| **Setup time**     | 30 seconds                                                          | Minutes to hours                      |
| **Maintenance**    | Managed by AIsa team                                                | Yours to maintain                     |
| **API coverage**   | AIsa's public catalogue                                             | Any API you can reach                 |
| **Customisation**  | Use as-is                                                           | Fully custom instructions and scripts |

***

## Use a pre-built skill when…

**The capability already exists in the registry.** If you need web search, financial data, Twitter/X access, image/video generation, or YouTube research — there's already a skill for it. Installing it takes one command and it comes with tested scripts and worked examples.

**You want the AIsa team to maintain it.** Pre-built skills are updated when the underlying APIs change. You don't have to track API deprecations or rewrite instructions when endpoints move.

**You're prototyping quickly.** `aisa skills install market` and a new Claude Code session is all you need to start querying live stock prices. Writing, testing, and maintaining an equivalent custom skill takes meaningfully longer.

### Example: install and use the market skill

```bash theme={null}
# Install
aisa skills install market

# Open a new agent session and ask:
# "Pull the last 30 days of NVDA price data and flag any days where
#  the move exceeded 5%. Cross-reference with earnings dates."
```

The agent reads the `market` skill description, loads the `SKILL.md` instructions, runs the bundled Python client, and calls AIsa's finance API — without you writing any code.

***

## Write a custom skill when…

**You need to call your own internal APIs.** Pre-built skills cover AIsa's public API catalogue. They can't query your company's internal data warehouse, CRM, or proprietary service. For those, write a SKILL.md that describes your internal endpoints and authentication.

**The existing skill doesn't cover your exact use case.** If you need a very specific workflow — a multi-step process combining several APIs in a particular order — a custom skill lets you encode exactly that sequence in the instructions body.

**You want to share domain-specific knowledge with the agent.** SKILL.md files aren't just API wrappers. You can include domain context, decision rules, output formatting requirements, and caveats that your team has learned from production use.

**You want to publish a skill for others.** Custom skills can be submitted to the [agent-skills](https://github.com/AIsa-team/agent-skills) registry as a pull request. If you've built something useful on top of AIsa APIs, contributing it benefits the whole ecosystem.

### Example: scaffold and edit a custom skill

```bash theme={null}
# Start from the closest built-in template
aisa skills init internal-crm --template default

# Edit the generated SKILL.md
# - Set name, description, and metadata
# - Write instructions that explain your CRM's auth and endpoints
# - Add example curl/Python commands for common queries
```

The `description` field is the most important line you'll write. It's what your agent reads at startup to decide when to activate the skill. Be specific about the trigger condition:

```yaml theme={null}
# ❌ Too generic — the agent won't know when to use this
description: "Internal CRM access."

# ✅ Clear trigger — the agent knows exactly when this applies
description: "Look up customer account details, support history, and
  renewal dates from the internal Salesforce CRM. Use when the user
  asks about a specific customer or account."
```

***

## Quick decision guide

```
Is there a pre-built skill in the OpenClaw registry for this?
│
├── YES → Does it cover your use case without modification?
│         ├── YES → aisa skills install <slug>
│         └── NO  → aisa skills init <name> (customise or extend)
│
└── NO  → Does it involve an AIsa public API not yet in the registry?
          ├── YES → aisa skills init <name> --template <closest>
          │         (and consider submitting a PR to agent-skills)
          └── NO  → aisa skills init <name> --template default
                    (write instructions for your internal API)
```

***

## What's next

* [Agent Skills](/agent-skills) — browse the full catalogue of pre-built skills
* [Quickstart](/agent-skills/quickstart) — install your first skill in 5 minutes
* [Standards](/agent-skills/standards) — how SKILL.md files work and how to author your own
* [Getting Started with AIsa](/guides/getting-started-with-aisa) — if you're new to the AIsa API