Agent Skills

fast-agent supports Agent Skills, and adds them from the following directories by default:

• .fast-agent/skills
• .agents/skills
• .claude/skills

When valid SKILL.md files are found:

• The Agent is given shell access with the working directory set to the workspace root.
• Skill descriptions from the manifest and path are added to the System Prompt using the {{agentSkills}} template variable. A warning is displayed if this is not present in the System Prompt.
• The /skills command lists the available skills.
• If duplicate skill names exist across directories, later directories override earlier ones, and a warning message is shown. (Use /status from an ACP Client to view).

Installing Skills

Skills can be installed, updated and removed from the CLI or TUI with the skills command.

To view available skills from the current marketplace, use /skills add to display a list. Supply either a path, repository URL, or skill name/index to install a skill.

Use /skills update to check current versions and install updates.

You can also install a skill directly from a GitHub SKILL.md URL or a local skill directory/file:

/skills add https://github.com/org/repo/blob/main/skills/example/SKILL.md
/skills add ./skills/example
/skills add ./skills/example/SKILL.md

fast-agent skills add https://github.com/org/repo/blob/main/skills/example/SKILL.md
fast-agent skills add ./skills/example
fast-agent skills add ./skills/example/SKILL.md

For direct installs, fast-agent reads SKILL.md first and uses the manifest name as the canonical install directory. Skills names must follow the format specified in the agentskills.io specification.

Registries and Marketplaces

fast-agent can install skills from online registries published in the Claude plugin format. By default, three registries are configured:

• fast-agent
• Hugging Face
• Anthropic

To browse and install skills from the marketplace:

/skills add

fast-agent skills add

This displays available skills with numbers. Install by name or number:

/skills add 1
/skills add skill-name

fast-agent skills add 1
fast-agent skills add skill-name

Removing Skills

Remove installed skills:

/skills remove skill-name
/skills remove 1

fast-agent skills remove skill-name
fast-agent skills remove 1

Managing Registries

In the TUI, view the current registry and available registries:

/skills registry

Example output:

# skills registry

Registry: https://github.com/huggingface/skills

Available registries:
- [1] https://github.com/huggingface/skills
- [2] https://github.com/anthropics/skills

Usage: `/skills registry [number|URL]`

In the TUI, switch registries by number or provide a custom URL:

/skills registry 2
/skills registry https://github.com/my-org/my-skills

For CLI commands, pass --registry to browse or install from a specific registry for that invocation:

fast-agent skills available --registry https://github.com/my-org/my-skills
fast-agent skills add skill-name --registry https://github.com/my-org/my-skills

Configuration

Configure skill directories and registries in fast-agent.yaml:

skills:
  directories:
    - ".fast-agent/skills"
  marketplace_urls:
    - "https://github.com/huggingface/skills"
    - "https://github.com/anthropics/skills"

See the Configuration Reference for details.

Command Line Options

If using fast-agent interactively from the command line, the --skills <directory> switch can be used to specify the directory containing skills. The --env <path> flag lets you relocate the entire environment directory (including the default skills folder).

# Specify a skills folder and a model
fast-agent go --skills ~/skill-development/testing/ --model "gpt-5-mini?reasoning=low"

# Give fast-agent access to the shell
fast-agent go -x

Config File

Use skills.directories to set multiple skills directories. When provided (even as an empty list), the default search paths are not used.

skills:
  directories:
    - ~/skills/team
    - ./skills/local

Programmatic Usage

Skills directories can be defined on a per-agent basis:

from fast_agent.constants import DEFAULT_SKILLS_PATHS

# Define the agent
@fast.agent(instruction=default_instruction, skills=DEFAULT_SKILLS_PATHS + ["~/source/skills"])
async def main():
    # use the --model command line switch or agent arguments to change model
    async with fast.run() as agent:
        await agent.interactive()

This allows each individual agent to use a different set of skills if needed. To disable skills for an agent, pass skills=[].