MCP request.params._meta support for

[codefromthecrypt]

Description:

Right now we document these two mapping headers:

• OTEL_AIGW_METRICS_REQUEST_HEADER_ATTRIBUTES: Example: x-team-id:team.id,x-user-id:user.id
• OTEL_AIGW_SPAN_REQUEST_HEADER_ATTRIBUTES: Example: x-session-id:session.id,x-user-id:user.id

Semantically, at MCP, these would map to request.params._meta as propagation fields are comingled with trace identifiers there, just like in HTTP headers.

While #1342 will handle session-scoped mappings, it cannot solve request scoped. We should handle that at some point because soon MCP SDKs will expose request params generically.

Relevant Links:

#1342 - adds header support for MCP

The below are a partial list of SDKs which will certainly make meta propagation easier and therefore used in frameworks soon!
modelcontextprotocol/csharp-sdk#712
modelcontextprotocol/modelcontextprotocol#1318
modelcontextprotocol/python-sdk#1231