diff --git a/src/mcp/shared/_httpx_utils.py b/src/mcp/shared/_httpx_utils.py
index 251469eaa1..23b2667da5 100644
--- a/src/mcp/shared/_httpx_utils.py
+++ b/src/mcp/shared/_httpx_utils.py
@@ -29,12 +29,13 @@ def create_mcp_http_client(
 
     This function provides common defaults used throughout the MCP codebase:
     - follow_redirects=True (always enabled)
-    - Default timeout of 30 seconds if not specified
+    - Default ``timeout`` tuned for long-lived SSE streams (see ``timeout`` below).
 
     Args:
         headers: Optional headers to include with all requests.
-        timeout: Request timeout as httpx.Timeout object.
-            Defaults to 30 seconds if not specified.
+        timeout: Request timeout as httpx.Timeout object. Defaults to 30 seconds for
+            connect/write/pool and 300 seconds for read (to accommodate long-lived
+            SSE streams) if not specified.
         auth: Optional authentication handler.
 
     Returns: