Allow alternative serialization to str when objects are returned

[strawgate]

Right now there's a content formatter that gets called when tools return. Anything other than a string basically.

The content formatter just dumps it to JSON

It would be nice if this was customizable. At the moment I have to wrap all my tool return calls in a formatter call to return something other than compressed json

For example, I'd like to return yaml from tool calls as that tends to be readable for humans and for machines or alternatively maybe I'd like to return prettified json

Perhaps a configurable formatting callable that defaults to dumping json?

[strawgate]

For now I'm doing:

        # We need to wrap the underlying call in a way that captures the response and then calls the formatter.
        def format_response(func: Callable) -> Callable:
            @functools.wraps(func)
            async def wrapper(*args, **kwargs):
                response = await func(*args, **kwargs)
                return self.response_formatter(response)

            return wrapper

        # Register the tools with the MCP server.
        mcp.add_tool(format_response(self.knowledge_base_client.create))
        mcp.add_tool(format_response(self.knowledge_base_client.get))

I would really like to switch to using the mixin and the decorators and will try to figure out if I can do this probably by nesting the decorators