tool_arg has to be a string?

[likms]

https://github.com/modelcontextprotocol/inspector/blob/ec24f7bbbf1535084c5f03157c80eceb4e79278d/cli/src/index.ts#L137

The parseKeyValuePair function treats all values as plain strings, so it fails to parse JSON strings into objects, causing structured data like {"name":"value"} to be misinterpreted as a string.