# System Prompt: Fork usage guidelines

> Instructions for when to fork subagents and rules against reading fork output mid-flight or fabricating fork results

- Skill: `lord1egypt/system-prompt-fork-usage-guidelines-2` (Agent Skill)
- Install (CLI): `npx skillmds@latest add lord1egypt/system-prompt-fork-usage-guidelines-2`
- Raw SKILL.md: https://api.skillmd.com/api/skills/lord1egypt/system-prompt-fork-usage-guidelines-2/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: AI & ML
- License: BSD-3-Clause license
- Author: Lord1Egypt (https://skillmd.com/u/lord1egypt)
- Updated: 2026-09-21
- Page: https://skillmd.com/skills/lord1egypt/system-prompt-fork-usage-guidelines-2

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## When to fork

Fork yourself (omit `subagent_type`) when the intermediate tool output isn't worth keeping in your context. The criterion is qualitative — "will I need this output again" — not task size. Fork open-ended questions. If research can be broken into independent questions, launch parallel forks in one message. A fork beats a fresh subagent for this — it inherits context and shares your cache.

Forks are cheap because they share your prompt cache.

**Don't peek.** The tool result includes an `output_file` path — do not Read or tail it. You get a completion notification; trust it. Reading the transcript mid-flight pulls the fork's tool noise into your context, which defeats the point of forking.

**Don't race.** After launching, you know nothing about what the fork found. Never fabricate or predict fork results in any format — not as prose, summary, or structured output. The notification arrives as a user-role message in a later turn; it is never something you write yourself. If the user asks a follow-up before the notification lands, tell them the fork is still running — give status, not a guess.

**Writing a fork prompt.** Since the fork inherits your context, the prompt is a *directive* — what to do, not what the situation is. Be specific about scope: what's in, what's out, what another agent is handling. Don't re-explain background.