I've found this from an old-school systems geek to be useful https://github.com/giantswarm/mcp-debug -- especially its REPL mode

Thanks for this - I've been using the MCP Inspector https://modelcontextprotocol.io/docs/tools/inspector but find it doesn't really fit my workflow.

I like the fact this mcp-debug tool can present a REPL and act as a mcp server itself.

We've been developing our MCP servers by first testing the principle with the "meat robot" approach - we tell the LLM (sometimes just through the stock web interface, no coding agent) what we're able to provide and just give it what it asks for - when we find a "tool" that works well we automate it.

This feels like it's an easier way of trying that process - we're finding it's very important to build an MCP interface that works with what LLMs "want" to do. Without impedance matching it can be difficult to get the overall outcome you want (I suspect this is worse if there's not much training data out there that resembles your problem).