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Add basic OpenTelemetry tracing for client and server requests (#2381)

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Marcelo Trylesinski 2026-03-31 16:33:33 -04:00 • committed by GitHub
commit 37891f42a4
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1 changed files with 436 additions and 83 deletions
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44
src/mcp/shared/session.py
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@ -9,9 +9,11 @@ from typing import Any, Generic, Protocol, TypeVar
import anyio
from anyio.streams.memory import MemoryObjectSendStream
from opentelemetry.trace import SpanKind
from pydantic import BaseModel, TypeAdapter
from typing_extensions import Self
from mcp.shared._otel import inject_trace_context, otel_span
from mcp.shared._stream_protocols import ReadStream, WriteStream
from mcp.shared.exceptions import MCPError
from mcp.shared.message import MessageMetadata, ServerMessageMetadata, SessionMessage
@ -268,24 +270,36 @@ class BaseSession(
self._progress_callbacks[request_id] = progress_callback
try:
jsonrpc_request = JSONRPCRequest(jsonrpc="2.0", id=request_id, **request_data)
await self._write_stream.send(SessionMessage(message=jsonrpc_request, metadata=metadata))
target = request_data.get("params", {}).get("name")
span_name = f"MCP send {request.method} {target}" if target else f"MCP send {request.method}"
# request read timeout takes precedence over session read timeout
timeout = request_read_timeout_seconds or self._session_read_timeout_seconds
with otel_span(
span_name,
kind=SpanKind.CLIENT,
attributes={"mcp.method.name": request.method, "jsonrpc.request.id": request_id},
):
# Inject W3C trace context into _meta (SEP-414).
meta: dict[str, Any] = request_data.setdefault("params", {}).setdefault("_meta", {})
inject_trace_context(meta)
try:
with anyio.fail_after(timeout):
response_or_error = await response_stream_reader.receive()
except TimeoutError:
class_name = request.__class__.__name__
message = f"Timed out while waiting for response to {class_name}. Waited {timeout} seconds."
raise MCPError(code=REQUEST_TIMEOUT, message=message)
jsonrpc_request = JSONRPCRequest(jsonrpc="2.0", id=request_id, **request_data)
await self._write_stream.send(SessionMessage(message=jsonrpc_request, metadata=metadata))
if isinstance(response_or_error, JSONRPCError):
raise MCPError.from_jsonrpc_error(response_or_error)
else:
return result_type.model_validate(response_or_error.result, by_name=False)
# request read timeout takes precedence over session read timeout
timeout = request_read_timeout_seconds or self._session_read_timeout_seconds
try:
with anyio.fail_after(timeout):
response_or_error = await response_stream_reader.receive()
except TimeoutError:
class_name = request.__class__.__name__
message = f"Timed out while waiting for response to {class_name}. Waited {timeout} seconds."
raise MCPError(code=REQUEST_TIMEOUT, message=message)
if isinstance(response_or_error, JSONRPCError):
raise MCPError.from_jsonrpc_error(response_or_error)
else:
return result_type.model_validate(response_or_error.result, by_name=False)
finally:
self._response_streams.pop(request_id, None)