Skills and Plugins

Equip CrabCode with task-specific capability bundles: UI design, browser automation, code review, skill authoring. Sources include bundled, user/project dirs, and the official marketplace.

What it is

A skill is a SKILL.md plus optional scripts/assets that teaches CrabCode how to handle a specific task ("when doing UI design, follow these principles", "for browser automation, drive this CLI"). At startup CrabCode indexes available skills by their frontmatter description; the model picks one when relevant.

A plugin is a release unit that bundles one or more skills, slash commands, and hooks together. Installing one plugin may register several skills.

When you see this doc

• The /plugin browse / install / manage screen
• /skills listing currently loaded skills
• /init recommending frontend-design / playwright / skill-creator
• A /plugin install foo@bar error or marketplace parse failure

Four sources of skills

CrabCode loads skills from four places at startup:

Tools exposed by MCP servers also surface in the available-skills list with an mcp source tag — see MCP.

Install official plugins

The official marketplace is crabcode-plugins-official — registered automatically once signed in, no manual setup.

/plugin                                                    # Main menu
/plugin install                                            # Browse all
/plugin install frontend-design@crabcode-plugins-official
/plugin install playwright@crabcode-plugins-official
/plugin install skill-creator@crabcode-plugins-official

/plugin                                                    # Main menu
/plugin install                                            # Browse all
/plugin install frontend-design@crabcode-plugins-official
/plugin install playwright@crabcode-plugins-official
/plugin install skill-creator@crabcode-plugins-official

CLI alternative (non-interactive):

crabcode plugin install <plugin>@<marketplace>
crabcode plugin uninstall <plugin>
crabcode plugin enable|disable <plugin>
crabcode plugin update [<plugin>]
crabcode plugin list

crabcode plugin install <plugin>@<marketplace>
crabcode plugin uninstall <plugin>
crabcode plugin enable|disable <plugin>
crabcode plugin update [<plugin>]
crabcode plugin list

Featured official plugins

Browse the full catalog with /plugin install.

Write your own skill

Directory layout

~/.crabcode/skills/<skill-name>/
  SKILL.md            # Required: frontmatter + prompt body
  helpers/            # Optional scripts / assets (reference via @ in the prompt)

~/.crabcode/skills/<skill-name>/
  SKILL.md            # Required: frontmatter + prompt body
  helpers/            # Optional scripts / assets (reference via @ in the prompt)

For a project-scoped skill, swap the root for <repo>/.crabcode/skills/<skill-name>/ and commit it alongside .crabcode/settings.json so teammates pick it up.

SKILL.md frontmatter fields

Everything after the frontmatter is the prompt body injected into the model.

Full example

---
name: ship-checklist
description: Prep changes for release — run lint, check changelog, verify PR template
when_to_use: User says "prep release" / "PR health check", or after git commit before opening a PR
allowed-tools: Read,Bash(bun*),Bash(cargo*),Bash(git status*)
effort: high
---

## Steps
1. Run the project's `bun run lint` / `cargo clippy`
2. Check CHANGELOG has an entry for this version
3. Check commit message matches project conventions
4. Warn if there are uncommitted changes

---
name: ship-checklist
description: Prep changes for release — run lint, check changelog, verify PR template
when_to_use: User says "prep release" / "PR health check", or after git commit before opening a PR
allowed-tools: Read,Bash(bun*),Bash(cargo*),Bash(git status*)
effort: high
---

## Steps
1. Run the project's `bun run lint` / `cargo clippy`
2. Check CHANGELOG has an entry for this version
3. Check commit message matches project conventions
4. Warn if there are uncommitted changes

Saving the file takes effect immediately. Run /skills to confirm it loaded, then /<skill-name> to invoke it manually and verify the prompt injection.

Not sure where to start? Run the bundled skillify skill — it walks you through generating a SKILL.md interactively.

Priority and conflict resolution

At startup CrabCode loads skills in this order (earlier wins; later same-name entries are dropped):

1. Managed (org-level policySettings)
2. User (~/.crabcode/skills/)
3. Project (<repo>/.crabcode/skills/)
4. Additional (extra working directories)
5. Plugin / Bundled / MCP

Duplicate same-name skills are logged as Skipping duplicate skill '<name>' to the debug log; launch with --debug to see the full loader trace.

Skill vs Hook vs MCP

All three extend CrabCode, but with different semantics:

Mixing is common — one plugin can ship a skill (teaches the model the approach) + a hook (PreToolUse to block dangerous ops) + an MCP server (adds new tools).

Custom marketplaces

Register your team's skill repo as a marketplace, then /plugin can install from it:

crabcode plugin marketplace add my-team/skills           # GitHub owner/repo
crabcode plugin marketplace add git@example.com:.../repo # Any git URL
crabcode plugin marketplace add ./local/path             # Local directory
crabcode plugin marketplace list
crabcode plugin marketplace update [<name>]
crabcode plugin marketplace remove <name>

crabcode plugin marketplace add my-team/skills           # GitHub owner/repo
crabcode plugin marketplace add git@example.com:.../repo # Any git URL
crabcode plugin marketplace add ./local/path             # Local directory
crabcode plugin marketplace list
crabcode plugin marketplace update [<name>]
crabcode plugin marketplace remove <name>

Or declare in settings.json:

{
  "extraKnownMarketplaces": {
    "my-team": {
      "source": "github",
      "repo": "my-team/skills",
      "ref": "main"
    }
  }
}

{
  "extraKnownMarketplaces": {
    "my-team": {
      "source": "github",
      "repo": "my-team/skills",
      "ref": "main"
    }
  }
}

Supported marketplace source values: github / git / url / npm / file / directory / settings (inline manifest).

Limits and caveats

• Read SKILL.md before installing: plugins may ship scripts and hooks — inspect the manifest first
• Refresh: /plugin marketplace update <name> pulls latest; plugin bodies update via /plugin update
• Scope: --scope user|project|local controls where it installs — project scope is committed via .crabcode/settings.json so teammates share it
• Collisions: same-name skill loaded later overrides earlier (project > user > bundled)
• Org policy: organizations can lock down allowed marketplaces and installable plugins via policySettings
• /plugins is an alias for /plugin

Related

• overview
• settings
• mcp