diff --git a/litellm/proxy/_experimental/mcp_server/mcp_debug.py b/litellm/proxy/_experimental/mcp_server/mcp_debug.py
index b25ed27becc..ff30ef99ebd 100644
--- a/litellm/proxy/_experimental/mcp_server/mcp_debug.py
+++ b/litellm/proxy/_experimental/mcp_server/mcp_debug.py
@@ -308,14 +308,18 @@ class MCPDebug:
 
     @staticmethod
     def wrap_send_with_debug_headers(
-        send: Send, debug_headers: Mapping[str, str], resolution: Callable[[], Mapping[str, str]] | None = None
+        send: Send,
+        debug_headers: Mapping[str, str],
+        resolution: Callable[[], Mapping[str, str]] | None = None,
+        *,
+        request_method: str | None = None,
     ) -> Send:
         """
         Return a new ASGI ``send`` callable that injects *debug_headers*
         into the ``http.response.start`` message.
         """
 
-        if resolution is not None:
+        if resolution is not None and request_method == "POST":
             return _DiagnosticSend(send, debug_headers, resolution)
 
         async def _send_with_debug(message: Message) -> None:
diff --git a/litellm/proxy/_experimental/mcp_server/server.py b/litellm/proxy/_experimental/mcp_server/server.py
index b53c55ef5fa..72d256e90fc 100644
--- a/litellm/proxy/_experimental/mcp_server/server.py
+++ b/litellm/proxy/_experimental/mcp_server/server.py
@@ -4482,7 +4482,9 @@ if MCP_AVAILABLE:
             diagnostics: Final = MCPAuthDiagnostics() if _debug_headers else None
             if diagnostics is not None:
                 scope[MCP_AUTH_DIAGNOSTICS_SCOPE_KEY] = diagnostics
-                send = MCPDebug.wrap_send_with_debug_headers(send, _debug_headers, diagnostics.headers)
+                send = MCPDebug.wrap_send_with_debug_headers(
+                    send, _debug_headers, diagnostics.headers, request_method=scope.get("method")
+                )
 
             # Ensure session managers are initialized
             if not _SESSION_MANAGERS_INITIALIZED:
diff --git a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_debug.py b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_debug.py
index 5039209c351..7d46bb0237a 100644
--- a/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_debug.py
+++ b/tests/test_litellm/proxy/_experimental/mcp_server/test_mcp_debug.py
@@ -208,20 +208,25 @@ class TestWrapSendWithDebugHeaders:
 
 @pytest.mark.asyncio
 @pytest.mark.parametrize("source", tuple(AuthResolution))
-async def test_debug_uses_resolution_recorded_after_response_start(source: AuthResolution) -> None:
+@pytest.mark.parametrize("method", ("GET", "DELETE", "POST"))
+async def test_debug_defers_resolution_until_first_frame_only_for_post(source: AuthResolution, method: str) -> None:
     captured: Final[list[Message]] = []
     diagnostics: Final = MCPAuthDiagnostics()
 
     async def send(message: Message) -> None:
         captured.append(message)
 
-    wrapped: Final = MCPDebug.wrap_send_with_debug_headers(send, {}, diagnostics.headers)
+    wrapped: Final = MCPDebug.wrap_send_with_debug_headers(
+        send, diagnostics.headers(), diagnostics.headers, request_method=method
+    )
     await wrapped({"type": "http.response.start", "status": 200, "headers": []})
-    assert captured == []
+    assert len(captured) == (0 if method == "POST" else 1)
     diagnostics.record("s1", source)
     body: Final[Message] = {"type": "http.response.body", "body": b"data: pong\n\n", "more_body": True}
     await wrapped(body)
-    assert dict(captured[0]["headers"])[b"x-mcp-debug-auth-resolution"] == source.value.encode()
+    assert dict(captured[0]["headers"])[b"x-mcp-debug-auth-resolution"] == (
+        source.value.encode() if method == "POST" else b"unresolved"
+    )
     assert captured[1] == body
 
 
@@ -233,7 +238,7 @@ async def test_early_stream_frame_reports_unresolved_without_waiting() -> None:
     async def send(message: Message) -> None:
         captured.append(message)
 
-    wrapped: Final = MCPDebug.wrap_send_with_debug_headers(send, {}, diagnostics.headers)
+    wrapped: Final = MCPDebug.wrap_send_with_debug_headers(send, {}, diagnostics.headers, request_method="POST")
     await wrapped({"type": "http.response.start", "status": 200, "headers": []})
     await wrapped({"type": "http.response.body", "body": b": ping\n\n", "more_body": True})
     diagnostics.record("s1", AuthResolution.stored_user_token)