Agent Skills
Add reusable skill packs to CUGA, try the PPTX skill, and choose a sandbox backend
Agent Skills
Agent skills are reusable instruction packs for specialized workflows. Each skill is a folder with a SKILL.md file, frontmatter, and optional helper files or scripts.
CUGA discovers skills at startup, lists short descriptions in the agent prompt, and exposes a load_skill tool so the model only loads the full instructions when the task needs them.
Reusable playbooks
Capture domain workflows once, then use them across tasks.
On-demand context
Keep prompts smaller by loading the full skill body only when it matches the task.
Sandbox-ready assets
Ship scripts and helper files with the skill so sandboxed runs can use them.
Where Skills Live
For project-local skills, use:
.agents/skills/**/SKILL.mdThis is the path written by the universal agent target in the skills CLI.
Global installs with -g go under ~/.config/agents/skills/. CUGA also scans legacy paths such as ~/.config/cuga/skills/ and <CUGA folder>/skills/.
Try It
From the CUGA repository root:
cuga start demo_skillsdemo_skills turns on skills and shell tooling for that run. By default, CUGA uses sandbox_mode = "native" from src/cuga/settings.toml, which runs through macOS sandbox-exec on macOS and falls back to local on other platforms.
This is the quickest way to verify skill discovery, load_skill, and bundled skill files without editing settings first.
Add the PPTX Skill
The Anthropic skills repository includes a pptx skill for creating, reading, and editing PowerPoint presentations.
Install the skill into the project-local universal agent skills folder:
npx skills add https://github.com/anthropics/skills --skill pptx -a universalStart the skills demo:
cuga start demo_skillsAsk CUGA to work with a deck, for example:
Create a 5-slide sales overview deck about our product roadmap.After install, the skill is available at:
.agents/skills/pptx/SKILL.mdUse -g if you want the skill globally available from ~/.config/agents/skills/ instead of only this project.
Sandbox Options
CUGA can run skill helper scripts through different sandbox backends. Choose the one that matches your environment.
Best for local development on macOS. This is the default in src/cuga/settings.toml.
[advanced_features]
sandbox_mode = "native"Run:
cuga start demo_skillsUse OpenSandbox when you want skills and shell-style tools to execute in a separate sandbox service, including remote or cloud-hosted isolation.
[advanced_features]
sandbox_mode = "opensandbox"Then run:
uv sync --extra opensandbox
cuga start demo_skillsWhen OpenSandbox is selected, demo_skills verifies the sandbox is reachable and syncs skill payloads into the sandbox workspace.
Use local mode only in trusted development environments. It runs shell-style tools directly on the host, so keep tool approval enabled for commands such as run_command.
[advanced_features]
sandbox_mode = "local"
enable_shell_tool = true
[policy]
enabled = trueThen run:
cuga start demo_skillsConfiguration Reference
For a persistent setup, configure the relevant sections in src/cuga/settings.toml:
[skills]
enabled = true
[advanced_features]
enable_shell_tool = true
sandbox_mode = "native" # "native", "opensandbox", "e2b", or "local"
[policy]
enabled = true| Setting | Use |
|---|---|
skills.enabled | Enables skill discovery, the load_skill tool, skill metadata APIs, and sandbox skill upload. |
advanced_features.enable_shell_tool | Enables shell-style tools such as run_command and write_file. |
advanced_features.sandbox_mode | Selects where shell-style skill helpers run. |
policy.enabled | Enables the policy system, including tool approvals. |
Use local only for trusted development environments. It runs directly on the host and should be paired with tool approval.
What Success Looks Like
When the demo is running, CUGA should discover installed skills, expose load_skill, and use the pptx skill automatically for PowerPoint tasks. If you choose OpenSandbox, bundled scripts and helper files are copied into the sandbox workspace before execution.