Claude Fable 5.1 made me a really nice animated pelican

On September 1st, 2026, Simon Willison published an article titled "Claude Fable 5.1 made me a really nice animated pelican" on his website. In the piece, Willison shared his experience with Anthropic's Fable 5.1 model, which they claim sets a new standard for coding, knowledge work, and long-running problem-solving tasks.

Willison began by noting that the model achieved a 52.6% score on the brand new Terminal-Bench-Science 0.1 benchmark, which was a significant improvement over previous models. He then proceeded to run a series of prompts through Fable 5.1 at various reasoning levels to observe the output.

For the low reasoning level, Willison found that Fable 5.1 appeared to skip reasoning entirely and produced an SVG of a pelican riding a bicycle. The output was generated in 23.8 seconds for a cost of 10.017 cents. Interestingly, when he ran the same prompt at the medium reasoning level, the output token count was 21 tokens less, indicating that Fable 5.1 may have skipped reasoning at this level as well.

As the reasoning level increased, so did the output from Fable 5.1. At the xhigh level, the model took 7 minutes and 51 seconds to generate an SVG with 65,927 output tokens. This version included a pelican with detailed features such as a long neck, orange beak, and intricate wings, as well as a bicycle with realistic elements like spokes, wheels, and handlebars.

At the max reasoning level, Fable 5.1 produced the most impressive result, taking 13 minutes and 54 seconds to generate a 65,927 token SVG. This version featured added details such as a darker tip region representing the primary feathers, a more natural-looking trail edge, and a helmet for the pelican to match the bicycle theme. Willison noted that while the output was still not as detailed as some other models, it was still an improvement over previous iterations.

The article concludes with Willison pondering potential additional enhancements, such as adding a scarf or cap for the pelican, or adjusting the handlebar curve for a more realistic appearance. He also mentions a discussion on Hacker News about the possibility of creating an animated version of the pelican, which he chose not to do due to additional costs.