Ah I see, that makes sense, tagging with @ would really help use a specific tool. Doesnt it work if you just mention the mcp and tool? it should.
I got it working by telling Cursor not to use curl and also prompted “you are the Cursor IDE and you can connect to locally running MCP servers”
I found at least 1 issue where something goes wrong with claude for mcp calls with no parameters, can add this rule which might help on some situations - not sure if this is the real reason its failing its hard to get it to be honest about what is going on 
- MCP Tool usage requirements *
MCP Tool Rule:
For tools with only optional parameters: Always provide at least one parameter explicitly. Never call with empty {} or no parameters.
Example:
100
This prevents JSON serialization failures in MCP implementations.
thanks that fixed it for me, wasn’t in agent mode