Comment by the_mitsuhiko

> * Contrary to APIs, they can change their interface whenever they want and with little consequences.

I already made this argument before, but that's not entirely right. I understand that this is how everybody is doing it right now, but that in itself cause issues for more advanced harnesses. I have one that exposes MCP tools as function calls in code, and it encourages the agent to materialize composed MCP calls into scripts on the file system.

If the MCP server decides to change the tools, those scripts break. That is is also similar issue for stuff like Vercel is advocating for [1].

[1]: https://vercel.com/blog/generate-static-ai-sdk-tools-from-mc...