wtf is fable-advisor?

Fable Advisor is a plugin for Claude Code, the command line coding assistant from Anthropic, that changes how work gets split up between AI models. The idea is simple: run your main session on the most capable and most expensive model, called Fable 5, and have it act as an architect. That architect writes specs, makes decisions, and checks the final result, but it never types the actual code itself. Instead, the plugin routes implementation work to cheaper models through separate agents. A routine task goes to Grok 4.5 through the Grok command line tool. A task where correctness really matters, or where you want a second independent attempt to compare against, goes to GPT-5.6 through the Codex command line tool. Because the typing work is usually about ninety percent of a session's total output, letting cheaper models handle it saves a lot of cost while keeping the expensive model focused on judgment calls. The plugin also includes an advisor agent, a read only second opinion that gets consulted before big decisions like architecture changes, migrations, or API designs, or whenever a problem has resisted two attempts. It reads the actual code but never edits it. To use it, you install the plugin through Claude Code's plugin marketplace command, then switch your session to run on Fable 5. There is also a lighter option: copy a single advisor file into your personal agents folder and keep your main session on a cheaper model like Sonnet, getting occasional expert consults without the full routing setup. Using the Grok or Codex lanes requires installing and logging into their respective command line tools separately, without them, those specific lanes report themselves as unavailable rather than silently switching to another model.