A Reddit user got Claude Fable 5.1 to build a Minecraft mod for $20.54

Two YouTube links and $20.54 later, a lightning dragon from Naruto was flying around Minecraft.

What the user did

The post went up on r/ClaudeAI on September 2, 2026. The author wanted a gun that fires Kirin, the lightning dragon from the anime, so he gave Claude Fable 5.1 a clip of the scene and a short of an existing railgun mod and asked it to combine them. According to the post, the model went through both videos frame by frame, wrote the mod for Fabric 1.21.1, modeled the dragon in Blender through the Blender MCP bridge, made the gun model and textures, and launched the game on its own.

The first version needed one round of fixes. The author recorded himself playing, sent the video back, and the model corrected the dragon flying upside down, doubled its size and added debris, a crater and fire. The totals he reported: about 383,600 output tokens, $20.54 through the API, and under an hour of wall-clock time. The mod is free on GitHub.

The same $20, seen from the other side

One day earlier, Anthropic’s launch of Fable 5.1 drew complaints because the model is not included in the $20 Pro subscription and costs extra credits there. This post is the other reading of that number: through the API, twenty dollars bought a finished mod that a human modder would spend a weekend on.

One caveat

The post’s setup line says the model ran inside an agent app whose team is active in the same threads, so the one-hour figure is best treated as a favorable case rather than an average. The tokens and the price, though, are the kind of numbers that are easy to check and hard to argue with.