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:

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

Open SKILL.mdRead the skill as plain markdown.

llms.txtAn index of these docs for language models.

llms-full.txtAll pages in one text file.

MCP serverGive an agent live tools instead of code to write.

Install it

Claude Code

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

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.

Other assistants

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.

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 describes every endpoint for code generators.

Tip

If your assistant supports MCP, the MCP server 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.