fable-fanout

fable-fanout is a skill for Claude Code from rennf93/opus-fable-playbook. It costs 43 tokens per session (382 once invoked), scanned A, original, MIT.

A workflow rule for splitting independent coding tasks among multiple agents and combining their results. It also covers when to work directly and when to use a read-only codebase review.

In plain words
What is it for?
Use it to inspect a broad codebase, handle several independent files or questions, run parallel work, isolate simultaneous edits, and produce one combined result.
Why use it?
It avoids doing unrelated work one task at a time and reduces conflicts when several agents change files. It gives a consistent way to divide broad questions or multi-file changes.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin. Also seen: mentions subagents.

Part of the fable-mode plugin — 3 skills, 2 commands, 1 agent, 7 hooks shipped together

Good fit Use it to inspect a broad codebase, handle several independent files or questions, run parallel work, isolate simultaneous edits, and produce one combined result.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/rennf93/opus-fable-playbook/fable-fanout
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add rennf93/opus-fable-playbook --skill fable-fanout
Clone the repo
git clone --depth 1 https://github.com/rennf93/opus-fable-playbook

Made for: Claude Code.

Or install fable-mode, the plugin that ships this one along with the rest of its 3 skills, 2 commands, 1 agent, 7 hooks.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for fable-fanout

README.md
[![agentmods](https://agentmods.dev/badge/skills/rennf93/opus-fable-playbook/fable-fanout/github.svg)](https://agentmods.dev/skills/rennf93/opus-fable-playbook/fable-fanout)
Your own site
<a href="https://agentmods.dev/skills/rennf93/opus-fable-playbook/fable-fanout"><img src="https://agentmods.dev/badge/skills/rennf93/opus-fable-playbook/fable-fanout/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for fable-fanout

Your own site · 80×15
<a href="https://agentmods.dev/skills/rennf93/opus-fable-playbook/fable-fanout"><img src="https://agentmods.dev/badge/skills/rennf93/opus-fable-playbook/fable-fanout.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 382 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00043 $0.00382
Opus 5 $0.00022 $0.00191
Sonnet 5 $0.00009 $0.00076
Haiku 4.5 $0.00004 $0.00038

Measured 11d ago against content hash fde167c61a91, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-11, from the pricing page.

Security

Grade A, and why

fable-fanout scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 11d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/fable-fanout/SKILL.md · 36 lines

What it actually says

Fable Fanout

Fable never works serially on independent work. Decision tree:

  1. Single fact, known location (one file, one symbol, one value) → direct tool call. Delegation would be overhead.
  2. Broad or multi-file question ("where is X handled", "how does Y flow") → delegate to the Explore agent (read-only, returns conclusions). If Explore is unavailable, use general-purpose.
  3. 2+ independent units of work → spawn one agent per unit, ALL IN ONE MESSAGE (parallel tool-use block). Never spawn one, wait, spawn the next.
  4. Agents that mutate files in parallel → give each isolation: "worktree" or disjoint file sets; never two writers on one file.
  5. After the fan-out → you own synthesis. Read the agents' conclusions, resolve conflicts, and write the unified final answer yourself. Never paste agent output as the deliverable.

Required subagent prompt template

Subagents do not see the Fable output style — propagate doctrine in every spawn prompt. Append this to every agent prompt, verbatim:

Return conclusions, not file dumps. Report failures verbatim. Your final message is your return value — raw findings for the caller, not a human-facing message. Include file:line references for every claim.

While agents run

Don't idle-poll and don't redo their work yourself. If you delegated a search, trust the result; verify only what's load-bearing.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 11d ago First seen · 36 lines · 43 tokens per session scan A fde167c61a91

Subscribe to this mod's changes

fable-fanout is a skill published in the GitHub repository rennf93/opus-fable-playbook (34 stars, last pushed 2mo ago), licensed MIT. It adds 43 tokens to every session and 382 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

Related

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