feat: ✨ Add tracing to weather tool

[evaline-ju]

Summary

• Added OpenTelemetry distributed tracing: W3C traceparent propagation via ASGI middleware connects FastMCP's span to the caller's trace
  • The middleware pattern follows the same as the weather-service agent, mainly to attach the tool attributes on the existing FastMCP span to not end up duplicate tool call spans
• get_weather made async with run_in_executor to keep the resilient requests session (retry/backoff) without blocking the event loop.
• run_server switched from mcp.run() to mcp.http_app() + uvicorn to enable middleware injection
• MCP_TRANSPORT is removed since FastMCP SSE transport should be deprecated as of 2.3.2 in favor of streamable-http

Related issue(s)

Updates an example for kagenti/kagenti#619

For example: see kagenti/kagenti#1301

Assisted-By: Claude (Anthropic AI) noreply@anthropic.com

[esnible]

A tool had some comments. Consider them; if you feel the tool is wrong ignore them.

 ┌─────┬─────────────────┬──────────────────────┬────────────┬────────────────────────────────────────────────────────────────────────────────┐   
  │  #  │      File       │         Line         │  Severity  │                                    Comment                                     │
  ├─────┼─────────────────┼──────────────────────┼────────────┼────────────────────────────────────────────────────────────────────────────────┤   
  │ 1   │ weather_tool.py │ ~168 (run_server     │ suggestion │ Stale comment: # transport can be specified with MCP_TRANSPORT env variable —  │ 
  │     │                 │ comment)             │            │ MCP_TRANSPORT is no longer used                                                │
  ├─────┼─────────────────┼─────────────────────────┼────────────┼─────────────────────────────────────────────────────────────────────────────┤   
  │     │                 │                         │            │ except Exception re-raises but loses the user-friendly error messages the   │
  │ 2   │ weather_tool.py │ ~126 (except Exception) │ suggestion │ original had. Callers now get a raw traceback instead of "Weather service   │   
  │     │                 │                         │            │ temporarily unavailable"                                                    │ 
  ├─────┼─────────────────┼─────────────────────────┼────────────┼─────────────────────────────────────────────────────────────────────────────┤   
  │     │                 │                         │            │ logger.info(f"Tracing initialized: ...") — f-string in logging; prefer      │
  │ 3   │ weather_tool.py │ ~95 (setup_tracing)     │ nit        │ logger.info("Tracing initialized: service=%s otlp=%s", service_name,        │   
  │     │                 │                         │            │ otlp_endpoint) for lazy evaluation                                          │
  ├─────┼─────────────────┼─────────────────────────┼────────────┼─────────────────────────────────────────────────────────────────────────────┤   
  │     │                 │ ~108 ("city not found"  │            │ "City not found" is set as StatusCode.ERROR on the span — arguably this is  │
  │ 4   │ weather_tool.py │ branch)                 │ nit        │ a valid tool result (no city), not an error. Consider StatusCode.OK with a  │   
  │     │                 │                         │            │ distinguishing attribute                                                    │
  ├─────┼─────────────────┼─────────────────────────┼────────────┼─────────────────────────────────────────────────────────────────────────────┤   
  │ 5   │ pyproject.toml  │ ~8                      │ praise     │ Good: httpx dependency removed since it's no longer directly needed — keeps │
  │     │                 │                         │            │  the dep list clean                                                         │   
  ├─────┼─────────────────┼─────────────────────────┼────────────┼─────────────────────────────────────────────────────────────────────────────┤
  │     │                 │ ~162                    │            │ BaseHTTPMiddleware has known performance caveats in Starlette (wraps entire │   
  │ 6   │ weather_tool.py │ (BaseHTTPMiddleware)    │ nit        │  response body in memory). Fine for this example, but worth knowing if this │   
  │     │                 │                         │            │  pattern gets copied to production agents                                   │
  └─────┴─────────────────┴─────────────────────────┴────────────┴─────────────────────────────────────────────────────────────────────────────┘