Add richer OTel MCP span attributes

src/mcp/server/lowlevel/server.py

@@ -73,6 +73,7 @@ async def main():
 from mcp.shared.session import RequestResponder
 
 logger = logging.getLogger(__name__)
+MCP_SESSION_ID_HEADER = "mcp-session-id"
 
 LifespanResultT = TypeVar("LifespanResultT", default=Any)
 
@@ -454,28 +455,38 @@ async def _handle_request(
         # Extract W3C trace context from _meta (SEP-414).
         meta = cast(dict[str, Any] | None, getattr(req.params, "meta", None)) if req.params else None
         parent_context = extract_trace_context(meta) if meta is not None else None
+        request_data = None
+        close_sse_stream_cb = None
+        close_standalone_sse_stream_cb = None
+        if message.message_metadata is not None and isinstance(message.message_metadata, ServerMessageMetadata):
+            request_data = message.message_metadata.request_context
+            close_sse_stream_cb = message.message_metadata.close_sse_stream
+            close_standalone_sse_stream_cb = message.message_metadata.close_standalone_sse_stream
+        request_headers = getattr(request_data, "headers", None)
+        session_id = request_headers.get(MCP_SESSION_ID_HEADER) if request_headers is not None else None
+        span_attributes: dict[str, Any] = {
+            "rpc.system": "mcp",
+            "rpc.service": self.name,
+            "rpc.method": req.method,
+            "mcp.method.name": req.method,
+            "jsonrpc.request.id": message.request_id,
+        }
+        resource_uri = getattr(req.params, "uri", None)
+        if resource_uri is not None:
+            span_attributes["mcp.resource.uri"] = str(resource_uri)
+        if session_id is not None:
+            span_attributes["mcp.session.id"] = session_id
 
         with otel_span(
             span_name,
             kind=SpanKind.SERVER,
-            attributes={"mcp.method.name": req.method, "jsonrpc.request.id": message.request_id},
+            attributes=span_attributes,
             context=parent_context,
         ) as span:
             if handler := self._request_handlers.get(req.method):
                 logger.debug("Dispatching request of type %s", type(req).__name__)
 
                 try:
-                    # Extract request context and close_sse_stream from message metadata
-                    request_data = None
-                    close_sse_stream_cb = None
-                    close_standalone_sse_stream_cb = None
-                    if message.message_metadata is not None and isinstance(
-                        message.message_metadata, ServerMessageMetadata
-                    ):
-                        request_data = message.message_metadata.request_context
-                        close_sse_stream_cb = message.message_metadata.close_sse_stream
-                        close_standalone_sse_stream_cb = message.message_metadata.close_standalone_sse_stream
-
                     client_capabilities = session.client_params.capabilities if session.client_params else None
                     task_support = self._experimental_handlers.task_support if self._experimental_handlers else None
                     # Get task metadata from request params if present

src/mcp/shared/session.py

@@ -272,11 +272,19 @@ async def send_request(
         try:
             target = request_data.get("params", {}).get("name")
             span_name = f"MCP send {request.method} {target}" if target else f"MCP send {request.method}"
+            span_attributes: dict[str, Any] = {
+                "rpc.system": "mcp",
+                "rpc.method": request.method,
+                "mcp.method.name": request.method,
+                "jsonrpc.request.id": request_id,
+            }
+            if (resource_uri := request_data.get("params", {}).get("uri")) is not None:
+                span_attributes["mcp.resource.uri"] = resource_uri
 
             with otel_span(
                 span_name,
                 kind=SpanKind.CLIENT,
-                attributes={"mcp.method.name": request.method, "jsonrpc.request.id": request_id},
+                attributes=span_attributes,
             ):
                 # Inject W3C trace context into _meta (SEP-414).
                 meta: dict[str, Any] = request_data.setdefault("params", {}).setdefault("_meta", {})

tests/shared/test_otel.py

@@ -37,8 +37,44 @@
     client_span = next(s for s in spans if s["name"] == "MCP send tools/call greet")
     server_span = next(s for s in spans if s["name"] == "MCP handle tools/call greet")
 
+    assert client_span["attributes"]["rpc.system"] == "mcp"
+    assert client_span["attributes"]["rpc.method"] == "tools/call"
     assert client_span["attributes"]["mcp.method.name"] == "tools/call"
+    assert server_span["attributes"]["rpc.system"] == "mcp"
+    assert server_span["attributes"]["rpc.service"] == "test"
+    assert server_span["attributes"]["rpc.method"] == "tools/call"
     assert server_span["attributes"]["mcp.method.name"] == "tools/call"
 
     # Server span should be in the same trace as the client span (context propagation).
     assert server_span["context"]["trace_id"] == client_span["context"]["trace_id"]
+
+
+@pytest.mark.filterwarnings("ignore::RuntimeWarning")
+async def test_resource_read_spans_include_resource_uri(capfire: CaptureLogfire):
+    """Verify that resource reads include MCP resource and RPC attributes."""
+    server = MCPServer("test")
+
+    @server.resource("test://resource")
+    def test_resource() -> str:
+        return "hello"
+
+    async with Client(server) as client:
+        result = await client.read_resource("test://resource")
+
+    assert result.contents[0].uri == "test://resource"
+
+    spans = capfire.exporter.exported_spans_as_dict()
+
+    client_span = next(s for s in spans if s["name"] == "MCP send resources/read")
+    server_span = next(s for s in spans if s["name"] == "MCP handle resources/read")
+
+    assert client_span["attributes"]["rpc.system"] == "mcp"
+    assert client_span["attributes"]["rpc.method"] == "resources/read"
+    assert client_span["attributes"]["mcp.method.name"] == "resources/read"
+    assert client_span["attributes"]["mcp.resource.uri"] == "test://resource"
+
+    assert server_span["attributes"]["rpc.system"] == "mcp"
+    assert server_span["attributes"]["rpc.service"] == "test"
+    assert server_span["attributes"]["rpc.method"] == "resources/read"
+    assert server_span["attributes"]["mcp.method.name"] == "resources/read"
+    assert server_span["attributes"]["mcp.resource.uri"] == "test://resource"