I have been working on this exact problem, and I suppose now is as good a time as any to talk about it.

To make any agent "good", there are two components: the model and the harness. Very few companies can train models, but anyone can build a harness. How much does the harness matter? Can I build a harness that's good enough that I can use open source models with opus level performance? That's the question I've been trying to answer by building better harnesses. None of the existing frameworks have the functionality I need to build a good harness. The features I need are language-level... and so I started building a language called Agency[0].

It's been six months and its going well. Some of the things Agency can do are wild:

- It can pause and serialize execution at any point, making HITL easy

- It has some neat safety capabilities such as handlers[1] and PFA[2]

- You can bundle up any agent as an HTTP or MCP server[3]

- I'm now working on a built-in optimizer to optimize agents (think DSPy).

Obviously, it's a huge undertaking, but having worked with the Agency for six months, I can't imagine going back to another framework. It makes things so easy. I'm working on its built-in agent now [4]. My goal it to get it to be as good as Claude Code, but using open source models. It's still early days, lots of rough edges, but if this sort of thing interests you, I'd love to have a few more people test it out.

[0] https://agency-lang.com

[1] https://agency-lang.com/guide/handlers.html

[2] https://agency-lang.com/guide/partial-application.html

[3] https://agency-lang.com/cli/serve.html

[4] https://github.com/egonSchiele/agency-lang/blob/main/package...