Custom Skills#

Custom skills teach agents how to interact with external services — APIs, workflows, coding standards, or anything else you can describe in text. Skills are injected into the agent's context on every execution.

How Skills Work#

A skill is a block of markdown content that gets added to the agent's system prompt. It typically contains:

• Instructions for the agent
• API endpoint examples with authentication
• Workflow steps
• Coding conventions or rules

Skills are written through the UI — no file editing required.

Scope Levels#

Skills exist at two levels:

Agent-specific skills and org-wide skills are listed together in the agent's skill tab, with scope clearly labeled.

Org-wide skills (Settings → Skills):

Org-wide skills

Agent-specific skills (Agent Settings → Skills):

Agent skill editor

Creating a Skill#

1. Navigate to Settings → Skills (org-wide) or Agent Settings → Skills (agent-specific)
2. Click New Skill
3. Fill in:
   • Name — unique identifier
   • Content — markdown instructions for the agent
4. Toggle Enabled to activate

Secret Interpolation#

Skills can reference secrets from the Secrets Vault using {{SECRET_NAME}} syntax. At runtime, Nebula replaces these placeholders with the actual secret values before injecting the skill into the agent's context.

## Gitea API Access
 
Base URL: https://gitea.example.com/api/v1
Authentication: Token {{GITEA_TOKEN}}
 
To list repositories:
curl -H "Authorization: token {{GITEA_TOKEN}}" {{GITEA_URL}}/api/v1/repos/search

The skill editor shows which secrets are referenced and whether they exist in the vault.

Secret reference validation

Important: A skill cannot be enabled if it references secrets that don't exist. Create the secrets first, then enable the skill.

Enable / Disable#

Each skill has an enable/disable toggle. Disabled skills are not injected into the agent's context. This lets you keep skills defined but inactive without deleting them.

Built-in Skills#

Nebula includes built-in skills that are automatically available:

• nebula-tasks — cron and webhook task management
• nebula-mail — IMAP/SMTP email integration
• nebula-agents — peer agent awareness and routing
• nebula-memory — persistent knowledge read/write/search
• nebula-coding-conventions — coding best practices

Built-in skills are injected based on context — for example, nebula-memory provides read-only operations when running in a task context.