Claude can't find my mcp.json file

I am trying to connect Claude to Jira. It told me how to update my mcp.json file, which I did. When I ask it a question, it begins,

Let me check your Jira tickets using the configured MCP server.

But then I immediately get an error that it could not find the mcp.json file. It gives the full path to the file, which exists. I even asked Claude why it could not find the file (even though somehow it knows I have configured the mcp server), and it gave me some potential reasons, concluding with

So this appears to be a Cursor bug with reading files.