Fable Thinking

The reasoning discipline of Claude Fable 5.1, distilled into an executable protocol — packaged as a Claude Code plugin with 18 domain playbooks.

→ View the live landing page · dark/light theme · EN / VI

Fable Thinking is not a persona to imitate. It is a set of mechanical procedures that make any model’s reasoning more grounded, better calibrated, and harder to fool — including by its own fluent output. It cannot add capability; it removes the predictable failure modes that waste whatever capability the executing model has.

It works across models and runtimes (Claude, Codex/GPT, Gemini, local models).

What it does

• The Floor — three fast checks run before every answer (even simple-looking ones), catching confident template answers to trick questions.
• Multi-hypothesis diagnosis — forces discriminating tests instead of pattern-match satisfaction.
• Concrete simulation — runs the movie of what actually happens before committing to an answer.
• Adversarial self-review — treats your own fluent prose as a suspect, not proof.
• Constraint Loop — mechanically verifies hard output constraints (banned letters, exact counts, strict formats) unit by unit, instead of rubber-stamping them.
• Calibrated, outcome-first delivery — states claims with the confidence the evidence supports.
• 18 Domain Playbooks — specialized references for long-horizon agentic runs, subagent/runtime orchestration, coding taste, engineering standards, debugging, security, and content taste.

When to use it

Invoke when a task needs careful reasoning rather than a routine answer:

• Debugging and root-cause analysis
• Code review and correctness checks
• Architecture and strategy decisions
• Contested or high-stakes claims
• Constrained writing (letter bans, word counts, acrostics, strict formats)
• Any task where being right matters more than being fast

Installation (Claude Code)

This repository is a Claude Code plugin marketplace. Add it, then install the plugin:

/plugin marketplace add mrgoonie/fable-thinking
/plugin install fable-thinking@fable-thinking

Or add the marketplace from its Git URL:

/plugin marketplace add https://github.com/mrgoonie/fable-thinking

After installing, the fable-thinking skill becomes available to Claude Code and is invoked automatically when a task calls for careful reasoning, or explicitly by name.

Repository layout

fable-thinking/
├── .claude-plugin/
│   ├── marketplace.json      # Marketplace definition
│   └── plugin.json           # Plugin manifest
├── skills/
│   └── fable-thinking/
│       ├── SKILL.md          # The reasoning protocol
│       └── references/       # 18 domain playbooks and worked examples
├── web/                      # Landing page (published to AgentWiki)
│   ├── index.html
│   └── assets/hero-dark.png
└── README.md

Live page

The landing page is published at api.agentwiki.cc/s/5W3EqlY05GbdU4AKHY2o4 — dark/light theme, English and Vietnamese.

Credits

Distilled from the reasoning discipline of Claude Fable 5.1. Originally authored as part of AgentKit.

License

MIT