[MCP Bundle] Add Events support

[EdouardCourty]

The MCP Bundle could benefit from events being fired in some cases. (For example: an exception being thrown during the execution of a tool).
Like KernelEvents on a classic Symfony project, I think it could be very useful to have MCP-specific events.

I was thinking of firing an event when :

• A client connects
• Before and after when a capability is used (resource, tool, prompt)
• When a response is sent back to the client

What do you think?

[chr-hertel]

That's def interesting - which kind of use cases do you have in mind?

cc @CodeWithKyrian

[EdouardCourty]

I'd use them for special handling when a call fails for example, or to trigger certain logic when needed.

For example :

• A tool call could log in a specific channel, or store the error somewhere for further review
• Someone could want to trigger custom logic on every call (logging, storing, whatever)

I guess these could even be used to modify the response on the fly like when using Symfony's response events with ::setResponse()...

[EdouardCourty]

Update
I opened a PR on the SDK's repo : modelcontextprotocol/php-sdk#175, support for EventDispatcher is already there.