Skills

Skills are reusable prompt expansions that the agent can load on demand. They extend the agent’s capabilities without modifying its core tools. The format follows the Agent Skills open standard.

Using Skills

Toggle Skills On/Off

Use the /skills command to open a checkbox picker where you can enable or disable installed skills:

/skills

Install a Skill

Ask the agent to install a skill by name. The built-in skill-manager handles searching, downloading, and installing:

You: install skill: apple-notes

The agent will:

1. Search for the skill (via web search or known repositories).
2. Download it to a staging area (~/.fermi/skills/.staging/).
3. Inspect and validate the skill definition.
4. Move it to the skills directory.
5. Call the reload tool so the new skill becomes available.

Activating Changes

Skills are loaded into the session at startup. After you install, remove, or edit a skill on disk, the change does not take effect until skills are reloaded. There are three ways that happens:

• The agent calls the reload tool (it re-reads skills, MCP servers, and the system prompt from disk). The skill-manager does this for you as its final step.
• You toggle a skill in the /skills picker (which reloads).
• You start a new session.

When skills change after a reload, Fermi inserts a short <system-message> noting which skills are now available or gone — so the agent (and you) can see the new capability without re-reading the whole prompt.

Skill Directory Layout

Skills live in ~/.fermi/skills/:

~/.fermi/skills/
  skill-name/
    SKILL.md          # Required: YAML frontmatter + markdown instructions
    scripts/          # Optional: helper scripts
    references/       # Optional: reference docs
  .staging/           # Temporary work area (not loaded as a skill)

Creating a Custom Skill

A skill is a directory containing a SKILL.md file. The file has YAML frontmatter followed by markdown instructions.

SKILL.md Format

---
name: lowercase-hyphenated-name
description: One-line description of when to use this skill
disable-model-invocation: false   # Optional: true = only user can invoke via /name
user-invocable: true               # Optional: false = hidden from / menu, agent-only
---

Markdown instructions here.

Frontmatter Fields

Field	Required	Description
name	Yes	Lowercase letters, numbers, and hyphens only. Must start with a letter or number.
description	Yes	One-line description of when the skill should be used.
disable-model-invocation	No	If true, only the user can invoke this skill (via /name). Default: false.
user-invocable	No	If false, the skill is hidden from the / menu and only the agent can use it. Default: true.

Arguments

Skills can accept arguments from the user:

• $ARGUMENTS — the full argument string
• $ARGUMENTS[0], $ARGUMENTS[1], or $0, $1 — positional arguments

Example

Here is a simple skill that explains code with diagrams:

---
name: explain-code
description: Explains code with diagrams and step-by-step analysis.
---

When explaining code, follow this structure:

1. **Analogy**: Compare the code's behavior to something from everyday life
2. **Diagram**: Draw an ASCII diagram showing the flow, structure, or relationships
3. **Step-by-step walkthrough**: Walk through what happens at each stage
4. **Common pitfall**: Highlight one non-obvious mistake or misconception

If $ARGUMENTS refers to a specific file, read it first and then explain it.

Managing Skills

Removing a Skill

Ask the agent to remove it, or delete the directory manually:

rm -rf ~/.fermi/skills/skill-name

The skill disappears after the next reload (the agent’s reload tool, a /skills toggle, or a new session).

Workflow Summary

Action	How
Install from GitHub	Ask the agent: “install skill: name”
Create custom	Write a SKILL.md in ~/.fermi/skills/name/
Enable/disable	/skills command
Remove	Delete the directory, then reload (or start a new session)

The Built-in Skill Manager

The skill-manager is a special skill that comes bundled with Fermi. It is not user-invocable (you do not call it directly). Instead, it activates automatically when you ask the agent to find, install, or manage skills.

The skill manager knows how to:

• Search for skills via web search
• Clone repositories to the staging area
• Inspect and validate SKILL.md files
• Move skills from staging to the active directory
• Clean up git metadata
• Call the reload tool to activate the changes