Anthropic Releases Fable 5.2 and Mythos 5.2 Model Pair
Anthropic released Fable 5.2 and Mythos 5.2 today, with the llm-anthropic CLI plugin adding immediate support. Hands-on testing shows five reasoning levels from low to max, where xhigh produced the best SVG output while max exhausted 128,000 tokens on reasoning and failed to return an image, reproducing a known bug.
Full Report
Anthropic released Fable 5.2 and Mythos 5.2 today. I've added them to llm-anthropic, so you can now run prompts through Fable 5.2 like this:
uv tool install llm
llm install llm-anthropic
llm keys set anthropic
# paste key here
llm -m claude-fable-5.2 "Generate an SVG of a pelican riding a bicycle"I ran pelicans at all five reasoning levels - low, medium, high, xhigh, and max. You can see them all here - here's the best result I got, from xhigh:
max failed to return an image at all, running out of tokens after spending 128,000 thinking about them. That's the same bug that I saw with Opus 5.5 - but it's new for the Fable series, both Fable 5 and Fable 5.1 returned max effort pelicans just fine.
Tags: llm, anthropic, claude, generative-ai, pelican-riding-a-bicycle, ai, llms, claude-mythos-fable