craftbag

Discover, list, load, and explain Agent Skills (SKILL.md) for CLI and MCP hosts.

What it does

craftbag walks project and home skill trees (.agents, plus optional vendor trees for Claude, Cursor, Grok, and Bline). It then:

• catalogs skills (list)

• prints one skill body (load), or heading keys / one heading (load --outline, load --section KEY)

• explains why a skill would activate (why)

• checks a package (validate)

The same operations exist over MCP stdio (skills_list, skills_load, skills_why, skills_validate). Hosts can filter, rank, and load skills without taking a dependency on any one agent product.

Related MCP server: skills-mcp

Install

macOS and Linux (Homebrew):

brew install craftbag/tap/craftbag

Windows (Scoop):

scoop bucket add craftbag https://github.com/craftbag/scoop-bucket
scoop install craftbag/craftbag

Both commands install craftbag and craftbag-mcp. The MCP host then runs craftbag-mcp (on macOS GUI apps, use the full path if PATH is empty: /opt/homebrew/bin/craftbag-mcp).

From a Rust toolchain (crates.io):

cargo install --locked craftbag-cli
cargo install --locked craftbag-mcp

Library dependency:

craftbag = "0.2"

From git (unreleased tip):

cargo install --locked --git https://github.com/craftbag/craftbag craftbag-cli
cargo install --locked --git https://github.com/craftbag/craftbag craftbag-mcp

MSRV is 1.85.

Getting started

Default list walks cwd-to-git .agents/skills and $HOME/.agents/skills. Claude, Cursor, Grok, and Bline trees stay out of that walk until you pass --vendor. When .cursor/skills (or the matching directory for another vendor) is present and that vendor is off, the empty list names the flag: hint: .cursor/skills is present; pass --vendor cursor. This clone has no project .agents. When the .agents directories are absent, craftbag list exits 0 and says no skills were found. craftbag new NAME writes .agents/skills/NAME/SKILL.md with a matching name and a placeholder description. Point --path at the demo tree (same catalog as the demo GIF):

git clone https://github.com/craftbag/craftbag
cd craftbag
craftbag list --no-implicit-roots --path demo/workspace/.agents/skills --catalog
craftbag load review-pr --no-implicit-roots --path demo/workspace/.agents/skills
craftbag load review-pr --no-implicit-roots --path demo/workspace/.agents/skills --outline
craftbag load review-pr --no-implicit-roots --path demo/workspace/.agents/skills --section review-a-pull-request
craftbag why review-pr --no-implicit-roots --path demo/workspace/.agents/skills --context review
craftbag validate demo/workspace/.agents/skills/review-pr

--section review-a-pull-request passes the outline key. --outline prints that key before the heading Review a pull request. validate takes the package directory that contains SKILL.md, here demo/workspace/.agents/skills/review-pr. The collection folder demo/workspace/.agents/skills has no SKILL.md of its own, so validate on it exits 1 with directory is not a skill package (no SKILL.md). list --path on that folder still lists the packages inside it.

--path, --user-dir, and --ignore expand ~/ themselves, because MCP and a quoted command have no shell. ~//name stays under your home directory, the same as ~/name. A ~// remainder that is still a Windows drive path is refused, so it does not replace your home directory. A path that is not there is an unreadable skip and says the path does not exist. A symlink whose target is gone says dangling symlink. Explicit / and /.. are roots you named. A padded .. that collapses to /, such as /tmp/ .., is refused.

If craftbag is not on PATH yet, cargo build -p craftbag-cli --locked and use ./target/debug/craftbag in those commands.

In a project that already has skills under .agents/skills:

craftbag list --catalog
craftbag load NAME
craftbag why NAME --context review
craftbag validate ./path/to/my-skill

Claude, Cursor, Grok, or Bline trees are opt-in:

craftbag list --vendor claude --catalog

Demo

MCP

craftbag-mcp speaks JSON-RPC on stdio. Tools: skills_list, skills_load, skills_why, skills_validate. prompts/list and prompts/get expose skills whose user_invocable is true (the default) as MCP prompts. prompts/get returns the same text envelope as load. After brew install or scoop install, craftbag-mcp --help names the tools. A request with "id": null is answered with that id. A message that omits id is a notification and gets no response.

Claude Desktop (claude_desktop_config.json) and other hosts that take a stdio command:

{
  "mcpServers": {
    "craftbag": {
      "command": "craftbag-mcp",
      "args": ["--vendor", "claude"]
    }
  }
}

Launch --path, --vendor, --user-dir, and --no-implicit-roots are the walk when a tool call omits that field. The host cwd is still the implicit walk root unless you pass --no-implicit-roots. skills_load accepts outline and section (same as load --outline / --section KEY).

Library

use craftbag::{discover, DiscoveryOptions};

fn main() -> std::io::Result<()> {
    let cwd = std::env::current_dir()?;
    let report = discover(&cwd, &DiscoveryOptions::default());
    for skill in &report.skills {
        println!("{} {}", skill.name, skill.description);
    }
    Ok(())
}

implicit_roots is on by default (cwd-to-git .agents and $HOME/.agents). Set it to false and put collection roots in paths for leftover-only hosts. format_load_view can print an outline or one heading instead of the whole body.

Contributing

See CONTRIBUTING.md. Security reports go to SECURITY.md. Roadmap and governance are in ROADMAP.md and GOVERNANCE.md.

License

Apache-2.0 or MIT. You may choose either. See LICENSE and LICENSE-APACHE.