# Agent skills

An agent skill is a short markdown file that tells an AI coding assistant how to do a job. The Ship Jay skill teaches an assistant the authentication, the quote then buy flow, idempotency, error handling and the safety rules for spending, so the code it writes against the API is correct the first time.

The skill is a single file:

```text
https://shipjay.com/docs/skills/shipjay-api/SKILL.md
```

[Open SKILL.md](/docs/skills/shipjay-api/SKILL.md)
  [llms.txt](/docs/llms.txt)
  [llms-full.txt](/docs/llms-full.txt)
  [MCP server](/docs/mcp)
## Install it

Claude Code reads skills from folders in `~/.claude/skills/` (for all projects) or `.claude/skills/` in a project.

```bash
mkdir -p ~/.claude/skills/shipjay-api
curl -o ~/.claude/skills/shipjay-api/SKILL.md \
  https://shipjay.com/docs/skills/shipjay-api/SKILL.md
```

Start a new session and ask for something that involves shipping labels. Claude Code loads the skill when the task matches its description.
Most coding assistants can read a markdown file of instructions. Download the file and add it where your tool keeps rules or context, for example a project rules file, an `AGENTS.md`, or a custom instructions field.

```bash
curl -o SHIPJAY.md https://shipjay.com/docs/skills/shipjay-api/SKILL.md
```

Then point your assistant at it, or paste its contents into the instructions.
## What the skill covers

- Base URL, bearer auth and where keys come from.
- The quote then buy flow, and why a rate id cannot be reused after it expires.
- The `Idempotency-Key` header on purchases and how to build a good key.
- Error codes, `Retry-After` and request ids.
- Rules for spending money: never buy without approval, never log keys, prefer limited keys.

The skill does not contain a key and never needs one. Your own code reads the key from an environment variable.

## Language models and the docs

- `/docs/llms.txt` lists the pages with a short description of the product.
- `/docs/llms-full.txt` has the whole documentation in one file.
- Every page has a **Copy Markdown** button, and a **View in Markdown** link, for pasting a page into an assistant.
- The [OpenAPI file](https://shipjay.com/api/v1/openapi.json) describes every endpoint for code generators.

**Tip:** If your assistant supports MCP, the [MCP server](/docs/mcp) is often better than a skill for operational work such as checking tracking or quoting a shipment. Use the skill when the assistant is writing integration code.