Can't call tools

[WriterZephos]

Describe the bug
A clear and concise description of what the bug is.

Using the example tool in the readme and running that script to open a stdio server, you cannot call the tool with json_rpc. It returns an error.

To Reproduce
Steps to reproduce the behavior:

1. Copy the example tool script from the readme into a ruby file and run it: ruby <file.rb>
2. use json rpc in the same console to request the tool: `{"jsonrpc":"2.0","id":"2","method":"tools/call", "param":{"name":"example_tool"}}

Expected behavior
It should run the tool and give the proper output.

[atesgoral]

@WriterZephos Are you using param instead of params or was that a typo in the issue description?