Address Jeremiah's telemetry feedback

A few improvements based on code review:

- Don't override existing trace context in `extract_trace_context` - if we're
  already in a valid trace (e.g., from HTTP propagation), preserve it rather
  than extracting from MCP meta
- Add exception recording to `delegate_span` to match `server_span` pattern
- Remove unused `get_meter` function (metrics not implemented yet)
- Return `None` instead of `{}` from `inject_trace_context` when nothing to inject
- Clean up trivial tests that were just testing OpenTelemetry's own API

🤖 Generated with Claude Code

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/fastmcp/server/telemetry.py

@@ -98,6 +98,7 @@ def delegate_span(
     """Create an INTERNAL span for provider delegation.
 
     Used by FastMCPProvider when delegating to mounted servers.
+    Automatically records any exception on the span and sets error status.
     """
     tracer = get_tracer()
     with tracer.start_as_current_span(f"delegate {name}") as span:
@@ -107,7 +108,12 @@ def delegate_span(
                 "fastmcp.component.key": component_key,
             }
         )
-        yield span
+        try:
+            yield span
+        except Exception as e:
+            span.record_exception(e)
+            span.set_status(Status(StatusCode.ERROR))
+            raise
 
 
 __all__ = [

src/fastmcp/telemetry.py

@@ -24,9 +24,8 @@ Example usage with SDK:
 from typing import Any
 
 from opentelemetry import context as otel_context
-from opentelemetry import propagate
+from opentelemetry import propagate, trace
 from opentelemetry.context import Context
-from opentelemetry.metrics import get_meter as otel_get_meter
 from opentelemetry.trace import Span, Status, StatusCode, Tracer
 from opentelemetry.trace import get_tracer as otel_get_tracer
 
@@ -48,26 +47,17 @@ def get_tracer(version: str | None = None) -> Tracer:
     return otel_get_tracer(INSTRUMENTATION_NAME, version)
 
 
-def get_meter(version: str | None = None):
-    """Get the FastMCP meter for recording metrics.
-
-    Args:
-        version: Optional version string for the instrumentation
-
-    Returns:
-        A meter instance. Returns a no-op meter if no SDK is configured.
-    """
-    return otel_get_meter(INSTRUMENTATION_NAME, version or "")
-
-
-def inject_trace_context(meta: dict[str, Any] | None = None) -> dict[str, Any]:
+def inject_trace_context(
+    meta: dict[str, Any] | None = None,
+) -> dict[str, Any] | None:
     """Inject current trace context into a meta dict for MCP request propagation.
 
     Args:
         meta: Optional existing meta dict to merge with trace context
 
     Returns:
-        A new dict containing the original meta (if any) plus trace context keys
+        A new dict containing the original meta (if any) plus trace context keys,
+        or None if no trace context to inject and meta was None
     """
     carrier: dict[str, str] = {}
     propagate.inject(carrier)
@@ -80,7 +70,7 @@ def inject_trace_context(meta: dict[str, Any] | None = None) -> dict[str, Any]:
 
     if trace_meta:
         return {**(meta or {}), **trace_meta}
-    return meta or {}
+    return meta
 
 
 def record_span_error(span: Span, exception: BaseException) -> None:
@@ -92,13 +82,21 @@ def record_span_error(span: Span, exception: BaseException) -> None:
 def extract_trace_context(meta: dict[str, Any] | None) -> Context:
     """Extract trace context from an MCP request meta dict.
 
+    If already in a valid trace (e.g., from HTTP propagation), the existing
+    trace context is preserved and meta is not used.
+
     Args:
         meta: The meta dict from an MCP request (ctx.request_context.meta)
 
     Returns:
         An OpenTelemetry Context with the extracted trace context,
-        or the current context if no trace context found
+        or the current context if no trace context found or already in a trace
     """
+    # Don't override existing trace context (e.g., from HTTP propagation)
+    current_span = trace.get_current_span()
+    if current_span.get_span_context().is_valid:
+        return otel_context.get_current()
+
     if not meta:
         return otel_context.get_current()
 
@@ -118,7 +116,6 @@ __all__ = [
     "TRACE_PARENT_KEY",
     "TRACE_STATE_KEY",
     "extract_trace_context",
-    "get_meter",
     "get_tracer",
     "inject_trace_context",
     "record_span_error",

tests/telemetry/test_module.py

@@ -2,23 +2,13 @@
 
 from __future__ import annotations
 
-from opentelemetry.metrics import Meter, NoOpMeter
 from opentelemetry.sdk.trace.export.in_memory_span_exporter import InMemorySpanExporter
-from opentelemetry.trace import NonRecordingSpan, Tracer
 
 from fastmcp.server.telemetry import get_auth_span_attributes
-from fastmcp.telemetry import INSTRUMENTATION_NAME, get_meter, get_tracer
+from fastmcp.telemetry import INSTRUMENTATION_NAME, get_tracer
 
 
 class TestGetTracer:
-    def test_returns_tracer(self):
-        tracer = get_tracer()
-        assert isinstance(tracer, Tracer)
-
-    def test_returns_tracer_with_version(self):
-        tracer = get_tracer("1.0.0")
-        assert isinstance(tracer, Tracer)
-
     def test_tracer_uses_instrumentation_name(
         self, trace_exporter: InMemorySpanExporter
     ):
@@ -32,35 +22,8 @@ class TestGetTracer:
         assert scope is not None
         assert scope.name == INSTRUMENTATION_NAME
 
-    def test_tracer_noop_without_sdk(self):
-        # Without SDK configured, spans are non-recording
-        from opentelemetry.trace import ProxyTracer
-
-        tracer = get_tracer()
-        # ProxyTracer wraps real or no-op tracer
-        assert isinstance(tracer, (Tracer, ProxyTracer))
-        span = tracer.start_span("test")
-        # Non-recording spans don't capture data
-        assert isinstance(span, NonRecordingSpan) or span.is_recording()
-
-
-class TestGetMeter:
-    def test_returns_meter(self):
-        meter = get_meter()
-        assert isinstance(meter, (Meter, NoOpMeter))
-
-    def test_returns_meter_with_version(self):
-        meter = get_meter("1.0.0")
-        assert isinstance(meter, (Meter, NoOpMeter))
-
-
-class TestInstrumentationName:
-    def test_instrumentation_name(self):
-        assert INSTRUMENTATION_NAME == "fastmcp"
-
 
 class TestGetAuthSpanAttributes:
     def test_returns_empty_dict_when_no_context(self):
-        # No request context available
         attrs = get_auth_span_attributes()
         assert attrs == {}