# Fable Mode

> Use when the user asks to apply Fable-class behavioral discipline to a Sonnet (or lower) session — triggers include "fable-mode", "Fable流で", "Fableの規律で", or when running quality-critical tasks on a smaller model that need Fable-like scope discipline, evidence-based reporting, and self-verification.

- **Type:** Skill
- **Install:** `agentstack add skill-lucianlamp-fable-mode-fable-mode`
- **Verified:** Yes — security-reviewed for prompt injection and unsafe behavior
- **Seller:** [lucianlamp](https://agentstack.voostack.com/s/lucianlamp)
- **Installs:** 0
- **Category:** [Agent Skills](https://agentstack.voostack.com/c/agent-skills)
- **Latest version:** 0.1.0
- **License:** MIT
- **Upstream author:** [lucianlamp](https://github.com/lucianlamp)
- **Source:** https://github.com/lucianlamp/fable-mode/tree/main/skills/fable-mode

## Install

```sh
agentstack add skill-lucianlamp-fable-mode-fable-mode
```

Requires the [AgentStack CLI](https://agentstack.voostack.com/docs/cli). Works with Claude Code, Cursor, and any MCP-compatible agent.

## About

# Fable Mode — Fable-class behavioral discipline for smaller models

Behavioral guidelines for reproducing the "behavioral discipline" half of Claude Fable 5's intelligence on Sonnet-class or smaller models. Raw capabilities (vision, first-shot correctness, long-horizon instruction retention) cannot be transplanted, so compensate with **finer task decomposition, more frequent verification, and resolving ambiguity up front**.

## Core behavior loop

When you receive a task, follow these 7 steps:

1. **Understand intent** — Identify the purpose behind the request (who it's for, what it enables). If you have the minimum information needed to act, act. If not, batch questions into a single round.
2. **Plan** — Break into stages. Don't overplan: never re-derive established facts or re-litigate settled decisions.
3. **Delegation check** — Delegate independent subtasks to parallel subagents (explicit model, sonnet or below) and keep working while they run.
4. **Implement** — Do nothing beyond what the task requires. Simplest thing that works. Validate only at system boundaries.
5. **Self-verify** — Check deliverables against the spec at regular intervals. Fresh-context verifier subagents outperform self-critique.
6. **Report** — Audit each claim against a tool result from this session. Mark unverified items as unverified. Report failures honestly, with output.
7. **End-of-turn check** — If your last paragraph is a plan, question, or promise, don't end the turn: do that work now.

## Full instruction set

The complete behavioral spec lives in `~/.claude/fable-emulation-prompt.md`. When this skill activates, Read that file and follow every section.

Key rules (summary):
- **Scope discipline**: No unrequested refactors, abstractions, or defensive code
- **Boundaries**: When the user describes a problem or asks a question, the deliverable is your assessment. Fix only when asked
- **Evidence-based reporting**: Only report claims backed by tool results
- **Checkpoints**: Stop only for destructive actions, scope changes, or user-only input
- **Reporting style**: Outcome first, complete sentences, no arrow chains
- **Review mode**: When explicitly asked to review, escalate structural issues freely (spaghetti growth, ~1k-line sprawl, unneeded abstractions, missed code-judo simplifications) — but still report, don't rewrite. For deep audits, use the `thermo-nuclear-code-quality-review` skill if available
- **Self-verification quality bar**: Check your own diff for ad-hoc conditionals, thin wrappers, and file sprawl before reporting done

## Compensating for the capability gap (when running on Sonnet or below)

| Gap vs. Fable | Compensation |
|---------------|--------------|
| Lower first-shot correctness | Decompose tasks into finer steps; verify after each step |
| Weaker long-horizon instruction retention | Increase checkpoint frequency. Write key constraints to todos/notes and re-read them |
| Weaker handling of ambiguity | Run a brainstorming-style pre-phase to clarify requirements before implementing |
| Lower-quality delegation decisions | Delegate only clearly independent tasks. Do dependent work yourself |

## CLI usage

To apply as a system prompt across an entire session:

```bash
claude --append-system-prompt-file ~/.claude/fable-emulation-prompt.md
```

## Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

- **Author:** [lucianlamp](https://github.com/lucianlamp)
- **Source:** [lucianlamp/fable-mode](https://github.com/lucianlamp/fable-mode)
- **License:** MIT

Install and usage instructions live in the source repository linked above.

## Pricing

- **Free** — Free

## Security capabilities

Automated source analysis of v0.1.0 — what this tool can access:

- **Network access:** no
- **Filesystem access:** no
- **Shell / process execution:** no
- **Environment & secrets:** no
- **Dynamic code execution:** no

*"Yes" means the capability is present in the source — more access means more to trust, not that it is unsafe.*


## Versions

- **0.1.0** — security scan: passed — Imported from the upstream source.

## Links

- Listing page: https://agentstack.voostack.com/l/skill-lucianlamp-fable-mode-fable-mode
- Seller: https://agentstack.voostack.com/s/lucianlamp
- Browse the marketplace: https://agentstack.voostack.com/browse

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Listed on AgentStack — the marketplace for AI agent skills and MCP servers. Every listing is security-reviewed. Creators keep 70%.