Skills

A skill is a folder of instructions for one kind of task: filling a PDF form, writing a changelog, checking disk space. The model sees only each skill’s name and description until a request matches one. Then it loads the full instructions with the load_skill tool.

Skills use the Agent Skills folder format (see anthropics/skills for examples):

~/.config/kaja/marketplace/abilities/disk-check/
├─ SKILL.md         # frontmatter + instructions (required for a skill)
├─ reference.md     # any other text file the instructions point to
└─ scripts/df.sh    # scripts the model can run

---
name: disk-space
description: Report free disk space. Use when the user asks about disk usage or a full disk.
---

Run `scripts/df.sh` and summarize which filesystems are above 90%.
For thresholds per filesystem type, read reference.md.

Field	Purpose
`name`	the folder’s name again, as the Agent Skills format requires (editors that check SKILL.md files warn without it). Optional, but when it’s there it must match the folder
`description`	what the skill does and when to use it, up to 1024 characters. It’s all the model sees before loading
`sticky`	optional: `true` suggests keeping the instructions in the system prompt while a persona uses the ability

The folder name is the skill’s name (lowercase letters, digits and single hyphens, up to 64 characters), so a name is an identifier, not a title: put a readable title in the Markdown heading. A name that doesn’t match the folder makes the skill fail to load. Other frontmatter keys (license, metadata and so on) are allowed and ignored. The same folder can also hold the ability’s tool.toml, mcp.toml or tool.ts; those aren’t the skill’s files, and load_skill never serves them.

Writing your own

Create the folder under ~/.config/kaja/marketplace/abilities/ and it loads on the next start; a persona that lists it in abilities gets it. kaja abilities tags your own local. A skill with missing or broken frontmatter is listed with the reason, and the others still load.

How the model uses them

The system prompt lists every enabled skill’s name and description.
load_skill(name) returns the instructions, the skill’s folder and its other files.
load_skill(name, file) reads one of those files. Reads stay inside the skill folder, and file names match case-insensitively. Binary files, hidden files and backups (SKILL.bak.md) are never served.
Scripts run through run_command with the usual approval, which is why skills with a scripts/ folder are local-only.

A skill reaches the model only while a persona that lists its ability is active, which also decides whether it’s loaded on demand, kept in the system prompt (sticky) or left out.

Tools