Add JSON output to tool command

[adrianlzt]

Fixes #3

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[adrianlzt]

Example output:

❯ node --loader ts-node/esm --no-warnings=ExperimentalWarning bin/dev.js tool -j @modelcontextprotocol/server-everything add a=59 b=40
{
  "content": [
    {
      "type": "text",
      "text": "The sum of 59 and 40 is 99."
    }
  ]
}

[gavinuhma]

Hey @adrianlzt this looks great. Thanks!