Yet another MCP server with J

[Thomas McGuire]

I saw the recent tangentstorm MCP server for J access. This one is a bit different. I had Claude Code (after a couple of code reviews) set up an MCP server using JHS and the J app backend provides access to Finnhub.

It works for stock quotes when I run gpt-oss-120B on a local machine and regester the tool to the llama.cpp llama-server user interface. 

Interestingly Claude code basically wrote it's own server in J at first using JHS as a support library to decode the http. I had to teach Claude code that JHS was capable of receiving the connection and handing the GET or POST message to the application running under JHS. 

Right now it's only for local environments since it is also running the jijx interpreter as well. I didn't try to disable that feature of JHS it is helpful for debugging purposes. 

The goal is to be able to use J for these small MCP tools rather than going to FastMCP and python . It's also a nice test case for Claude code to program in J. I notice that I have to do a lot of "/btw" to let it know it's all mixed up on how J and JHS works. 

It's not too many lines of code given JHS is doing most of the heavy lifting. You can find it here if you are interested: https://github.com/tmcguirefl/jmcp

Tom McGuire