Fable Is Set Free - There’s A Brand New Claude In Town

As we initially covered yesterday, after some heavy lobbying by Anthropic, U.S. Commerce Secretary...

As we initially covered yesterday, after some heavy lobbying by Anthropic, U.S. Commerce Secretary Howard Lutnick lifted the restrictions on Fable 5 and Mythos 5 after fears that they could be too powerful.

The following day, Thariq Shihipar, a member of Claude's technical staff at Anthropic, and Cat Wu, the company's head of product for Claude, held a roundtable hosted by Simon Willison, founder of the Datasette open-source project, to promote the new model and sing the praises of its efficacy.

The Anthropic duo claimed that Fable blew past competitor models in terms of speed and efficiency, with agentic coding and code fixing particular strengths. In the latter case, it was dealing with 50% more pull requests for its engineers.

The complexity of the code that Fable can create is better than anything Anthropic has managed before, the team asserted. It can operate for longer without needing human input, check its own prompts by writing test scripts for software it has created, and handle visual information from embedded graphs and images in source material.

"It's good at the dynamic permissions that you yourself give inside of the prompt, which I think is really important," Shihipar said.

"It also works well with our sandboxing instructions because sandboxing is one of those things where there's so many different edge cases, and it's hard to determine if we follow them. But if you have a sandbox and something needs to escape like a network request, auto load can then look at that request and allow it if it makes sense."

Complex data analysis capabilities have been beefed up, it was said, again without having to constantly question the human operator. Working within an agent harness like Claude Code, it can delegate work to subagents for greater autonomy.

"In general, we try to keep the cardinality pretty low and make sure that every tool we add has a distinct function from every other tool, so that Claude can very easily distinguish when to call each for file edit," Wu explained.

"The reason that we have file edit is because back in the day we used to show, or I guess we still do, we show people when Claude makes a file change, and there's this nice dedicated UI that says, 'Do you approve this edit to this file?'"

Wu recounted how she'd been asked to join a Microsoft Teams meeting for the first time and decided to see if she could get Fable to do it for her. She asked it to set up an account and add the necessary contacts to the group. It added guests, wrote a welcome message, and contacted IT admins about restricted accounts, all in 30 minutes.

"I love this idea that configuring Microsoft Teams takes an advanced AI 30 minutes, that's fantastic," commented Willison.

One feature Wu was particularly keen on was remote control. Fable can be set up for a long process and left to get on with it but still be controlled by a separate laptop or smartphone.

"A lot of people tell me that they just plug their laptop into a power charger, close the screen, open a bunch of remote control sessions, watch the screen, and then use their mobile phone from their couch to control Claude," she recounted.

It's not all work, though. Shihipar admitted he'd used it to develop a 2D fighting game and build characters of his friends. Wu has a personal project to support her mountain-climbing habit, with an application that finds routes to scale, matches them to local Airbnbs, and plots the distance to the slopes from the nearest parking space. Neither application is scheduled for release.