Claude Fable is relentlessly proactive

11th June 2026

After two days of experience with Claude Fable 5 I think the best way to describe it is relentlessly proactive. It knows a whole lot of tricks and it will deploy pretty much any of them to get to its goal.

I’ll illustrate this with an example. I was hacking on Datasette Agent today when I noticed a glitch: a horizontal scrollbar that shouldn’t be there in the jump menu chat prompt. I snapped this screenshot:

Then I started a fresh claude session in my datasette-agent checkout, dragged in the screenshot and told it:

Look at dependencies to help figure out why there is a horizontal scrollbar here

Look at dependencies to help figure out why there is a horizontal scrollbar here

I had a hunch the cause was in a dependency of Datasette Agent (likely Datasette itself) and I knew Fable was good at digging into dependency code, either by inspecting installed files in its own virtual environment site-packages or by referencing a local checkout on disk. Telling it to start with dependencies felt like a good bet.

I got distracted by a domestic task and wandered away from my computer.

Whe...