Support object type tool result

[logan272]

Is your feature request related to a problem? Please describe.
Currently, the Tool Result can only return Text Content, Image Content, or Embedded Resources. However, there are many instances where I need the tool call to return a JSON object.

Describe the solution you'd like
I propose adding an object content type to the tool result, allowing for structured data to be returned directly. For example:

return {
   content: [
      {
           type: 'object',
           data: { ... }
      }
   ]
}

Describe alternatives you've considered
Currently, when I want to return structured data from a tool call, I have to use the following workaround, which is not ideal:

return {
   content: [
      {
           type: 'text',
           text: JSON.stringify(data)
      }
   ]
}