Agent Skills

fast-agent supports Agent Skills, and by default searches the directories listed in DEFAULT_SKILLS_PATHS (in this order):

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

When valid SKILL.md files are found:

The Agent is given access to execute and file reading tools.
Skill descriptions from the manifest and path are added to the System Prompt using the {{agentSkills}} expansion. 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. Warnings are surfaced in /status (ACP).

When using the interactive or CLI skill-management commands, the managed install directory defaults to the first entry in that search order (.fast-agent/skills) unless you override it in config or with --skills-dir or --env.

Skill Marketplace

fast-agent can install skills from online registries. By default, three registries are configured:

The active default marketplace is the fast-agent-ai/skills. There you will find skills to extend, automate and work efficiently with fast-agent.

Installing Skills

Use the /skills add command to browse and install skills from the marketplace:

/skills add

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

/skills add skill-name
/skills add 1

Removing Skills

Remove installed skills with /skills remove:

/skills remove skill-name
/skills remove 1

Updating Installed Skills

When installing skills from a registry, a manifest is created to help you keep your Skills up-to-date.

Check for updates to managed skills:

/skills update

Apply updates by name, number, or all managed skills:

/skills update skill-name
/skills update 1
/skills update all

Managing Registries

View the current registry and available registries:

/skills registry

Example output:

# skills registry

Registry: https://github.com/fast-agent-ai/skills/blob/main/marketplace.json

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

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

Switch registries by number or provide a custom URL:

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

Configuration

Configure default skill directories and registries in fastagent.config.yaml:

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

See the Configuration Reference for details.

`fast-agent skills` CLI

The standalone CLI exposes the same basic workflow outside the interactive prompt:

# List discovered local skills
fast-agent skills list

# Browse/search marketplace skills
fast-agent skills available
fast-agent skills search auth

# Install, remove, and update managed skills
fast-agent skills add skill-name
fast-agent skills remove skill-name
fast-agent skills update
fast-agent skills update all --yes

Use --registry to override the marketplace URL/path for a single command, and --skills-dir to override the managed install directory:

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
fast-agent skills add skill-name --skills-dir ~/skills/dev
fast-agent skills update all --skills-dir ~/skills/dev --yes

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.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=[].