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).
- 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.
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
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.
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
The landing page is published at api.agentwiki.cc/s/5W3EqlY05GbdU4AKHY2o4 — dark/light theme, English and Vietnamese.
Distilled from the reasoning discipline of Claude Fable 5.1. Originally authored as part of AgentKit.
