Skills with Claude Agent SDK

In Claude Agent SDK, skills are loaded from the filesystem and enabled through agent configuration.

What Agent SDK Requires

From official docs, to use skills in Agent SDK you must:

1. Allow the Skill tool in allowed_tools
2. Set setting_sources to include "user" or "project" (or both)
3. Store skills in supported filesystem locations (for example .claude/skills/...)

Unlike Claude Code CLI behavior, skills are not programmatically registered in Agent SDK.
They must exist as files on disk.

Minimal Configuration Pattern

{
  "allowed_tools": ["Skill"],
  "setting_sources": ["user", "project"]
}

How This Fits with Subagents

• Parent agent can orchestrate the task.
• Subagents can run isolated work with scoped tool access.
• Skills provide repeatable procedure inside each delegated step.

Use subagents for isolation/parallelization; use skills for consistency.

Best Practices

• Keep skill scope narrow and composable.
• Store skills in project scope when they are repo-specific.
• Use user scope for personal reusable skills.
• Test activation behavior with representative prompts before production.