Agent skill · software engineering · jeremylongshore
agent-creator
Create production-grade agent .md files aligned with the current Anthropic
Why this skill is useful
Adds validation scripts and a structured approach for creating agents that comply with the Anthropic 2026 schema, which the AI cannot generate on its own.
What it needs
Requires claude-code installed locally. About 9k tokens when loaded. Last updated 2026-08-07. 2,604 stars on the source repository.
What this skill does
Agent Creator Creates spec-compliant agent .md files following Anthropic's current documented subagent frontmatter contract. Supports both creation of new agents and validation of existing ones. Overview Agent Creator fills the gap between ad-hoc agent files and production-grade agents that pass marketplace validation. It distinguishes the 16 fields in Anthropic's public frontmatter table from runtime-recognized experimental options, then layers the stricter Intent Solutions required set on top. It prevents common mistakes (using allowed-tools instead of disallowedTools, adding invalid fields like capabilities or expertiselevel), and produces agents with substantive body content that actually guides Claude's behavior. Key difference from skill-creator: agents support both tools (allowlist) AND disallowedTools (denylist). Skills use allowed-tools (allowlist) and, since schema 3.7.0, an optional kebab-case disallowed-tools denylist — a parallel field, not a unification. Agents also support effort, maxTurns, skills, memory, isolation, permissionMode, background, color, and initialPrompt — fields that don't exist for skills. Claude Code also recognizes a separately labeled runtime experimental object; do not present it as part of the public 16-field table. The agent body becomes the system prompt that drives the subagent — it does NOT receive the full Claude Code system prompt. Field-naming warning: Agents use camelCase disallowedTools: (canonical sub-agents spec); skills use kebab-case disallowed-tools: (schema 3.7.0+). The validator rejects either mismatch — never copy-paste between agent and skill frontmatter without renaming. …
How to use it
Reference it in AdaL, Claude Code, Cursor or any coding agent — nothing to install:
@skills jeremylongshore/agent-creator