Claude Agent Creator

Build precise, focused, production-grade Claude agents without re-researching the platform. The default product is a Claude Code subagent: a Markdown file with YAML frontmatter plus a system-prompt body, stored under .claude/agents/ (project) or ~/.claude/agents/ (personal), that Claude automatically delegates to when a task matches its description. The subagent runs in its own fresh context window, with its own tools and model, and returns only a summary.

Scope: this skill creates the agents that do work. For repo instruction files (AGENTS.md/CLAUDE.md) use agent-md-creator; for portable Agent Skills use skill-creator; for OpenCode agents use opencode-agent-creator. A subagent often preloads a Skill to get its methodology — the two compose via the skills: field. For a cloud/programmatic agent on the Claude API, see references/managed-agents.md.

The five things that define an agent

Internalize this — every decision below maps to one of these:

1. Identity — name (lowercase-hyphens; how Claude and @-mentions address it).
2. Routing — description (third person; the trigger that makes Claude delegate).
3. Capability boundary — tools / disallowedTools / mcpServers / skills (what it can touch).
4. Brain — model (cost vs. capability: haiku / sonnet / opus / fable / inherit).
5. Behavior — the Markdown body (the system prompt: role, workflow, output contract).

The one constraint that shapes every prompt

A subagent starts cold. It does not see the conversation history, the files Claude already read, or the skills already invoked. Its entire world at startup is: its own system-prompt body, the one-shot delegation message Claude writes, the CLAUDE.md hierarchy, a git-status snapshot, and any skills: you preload. Any context the agent needs must be in the body, in the description, preloaded as a skill, or restated in the task you delegate — otherwise it does not cross. (The built-in Explore and Plan agents skip even CLAUDE.md.) Design as if briefing a brand-new contractor who can read the repo but was in none of your meetings.