Agent Creator

Agent Creator

Use this skill when the user wants a new reusable agent added to this repository, not just a one-off spawned subagent for the current turn.

Goal

Create repo-local agent definitions under .codex/agents that match the patterns already used in this codebase.

Local conventions

• Agent files live at .codex/agents/<slug>.toml.
• Keep filenames lowercase and hyphen-safe. Use a user-facing name inside the file.
• Required fields: name, description, model, model_reasoning_effort, sandbox_mode, and developer_instructions.
• Add nickname_candidates when the role is collaborative or likely to be spawned often.
• Use [[skills.config]] only when the agent has a repeatable workflow that should load a repo-local skill automatically.
• Add [mcp_servers.*] blocks only when the role truly depends on an MCP server.

Recommended defaults

• Use gpt-5.4-mini with medium reasoning for focused specialists.
• Use gpt-5.4 when judgment quality matters more than speed, such as reviews or research-heavy roles.
• Use read-only for QA, exploration, docs, and review agents.
• Use workspace-write only for builder or repair agents that are expected to edit files.
• Keep developer_instructions short, imperative, and role-specific.

Workflow

1. Inspect the closest existing agent in .codex/agents and copy its style.
2. Lock the minimum spec from the request: role name, description, sandbox mode, model/reasoning, edit permissions, and whether the agent should auto-load a skill.
3. If a detail is missing, infer it from the nearest existing agent and state that assumption after the work is done.
4. Scaffold the base TOML with the script in scripts/init_agent.mjs.
5. Patch the generated file for any repo-specific details such as nickname_candidates, MCP blocks, or linked skills.
6. If the new role needs a repeatable workflow and no fitting skill exists yet, create a matching skill in .codex/skills/<skill-name> in the same turn.
7. Read the finished file back and sanity-check that it matches the repo's existing agent style.

Scaffold command

node .codex/skills/agent-creator/scripts/init_agent.mjs \
  --slug qa-helper \
  --name "QA Helper" \
  --description "Browser-first QA assistant for lightweight smoke tests." \
  --model gpt-5.4-mini \
  --reasoning medium \
  --sandbox read-only \
  --nicknames "QA,Helper" \
  --instructions "Act as a lightweight QA helper.\nCheck key routes, capture evidence, and avoid code edits unless asked."

Script behavior

• By default the script writes .codex/agents/<slug>.toml.
• Pass --skill-path .codex/skills/<skill-name> to add an enabled [[skills.config]] block.
• Pass --dry-run to print the TOML without writing files.
• If the target file already exists, the script stops unless --force is passed.

Deliverable

Return the new agent file path, the main behavior choices you encoded, and any assumptions you made while filling in missing details.