Fable 5.1 vs fable 5 vs opus 5

cool experiments by @thehypedotnews

the test gave Fable 5, 5.1, and Opus 5 the same reference scenes and asked each to recreate them procedurally from scratch in Three.js.

Fable 5 was both the cheapest and the fastest, but fable 5.1 stood out on visual detail.

This test also exposed a token constraint because Fable 5.1 spent 102,116 tokens reasoning and hit its output ceiling before finishing the file.

Anthropic documents a 128K maximum output for Fable 5.1, and current-turn thinking counts against that same limit, so heavy reasoning can leave less room for code. If the model spends too much of it thinking, it can hit the 128k limit before finishing a large codebase.