jq cannot be just an MCP, unless it's acceptable that yuo pass all data through the context. If that's not acceptable and you want to have it as tool, then you need some other way to handle the data.

I think the basic solution to this is to have a "static shell" but with modern tools for the agents, not actually executing other binaries. It could have things like jq, curl, piping and redirection to/from session files. Maybe even Python if it can be made safe. If not, then there are a lot of languages can be.