This is what I’ve been doing too. Give the LLM a link to an OAS for an API and let it use curl for everything after that. I don’t even wrap the API or use restish all, the LLM knows how to use curl well enough.

This lets me add quick skills that are essentially just: “this is the OAS link, this is how you store and use the authorization, this is when I want you to use it”. That combined with pointing it at the documentation for common workflows and usage examples, and it’s been great.

The only thing I’ve had trouble with is auth really. MCPs are treated as first class citizens by most model provider’s agents and trying to provide a shell-based alternative for hiding the secret credentials from the LLM has been difficult.

I've been beating this drum for the last 8 months.

The next frontier is using hooks to guide agents to use tools better and avoid doom loops.

Of all the interface modalities available, CLIs seem like the most natural for copilots to work with. Lots of examples in the training data, universal interface for help, maps well to the sequential nature of token generation, similar syntax for different OSs… I can see them replacing skills and MCP et al from the model’s perspective.