Suggest: change response from LIST to JSON for tools list_prometheus_label_names, list_prometheus_label_values...

[spirent-gavin]

These tools work well and return a list. But more and more AIs ask mcp tools to return json response.
I strongly recommend to update those tools to return json response.

mcp-grafana version: 0.6.3
Example:
tool: list_prometheus_label_names
response:
{
"content": [
{
"type": "text",
"text": "["aaa","bbb","ccc"]"
}
]
}

text is a list.
Expect text to be valid json or json array.

Thanks