diff --git a/packages/smithy-core/.changes/next-release/smithy-core-enhancement-20251124183509.json b/packages/smithy-core/.changes/next-release/smithy-core-enhancement-20251124183509.json
new file mode 100644
index 000000000..56a70a6c1
--- /dev/null
+++ b/packages/smithy-core/.changes/next-release/smithy-core-enhancement-20251124183509.json
@@ -0,0 +1,4 @@
+{
+  "type": "enhancement",
+  "description": "Improved default error message for instances of ClientTimeoutError."
+}
\ No newline at end of file
diff --git a/packages/smithy-core/src/smithy_core/aio/client.py b/packages/smithy-core/src/smithy_core/aio/client.py
index 01f18097b..6060727b4 100644
--- a/packages/smithy-core/src/smithy_core/aio/client.py
+++ b/packages/smithy-core/src/smithy_core/aio/client.py
@@ -469,9 +469,7 @@ async def _handle_attempt[I: SerializeableShape, O: DeserializeableShape](
                     )
             except Exception as e:
                 if isinstance(e, self.transport.TIMEOUT_EXCEPTIONS):
-                    raise ClientTimeoutError(
-                        message=f"Client timeout occurred: {e}"
-                    ) from e
+                    raise ClientTimeoutError(message="A timeout error occurred.") from e
                 raise
 
             _LOGGER.debug("Received response: %s", transport_response)
diff --git a/packages/smithy-http/.changes/next-release/smithy-http-enhancement-20251122132342.json b/packages/smithy-http/.changes/next-release/smithy-http-enhancement-20251122132342.json
new file mode 100644
index 000000000..d7b9f982e
--- /dev/null
+++ b/packages/smithy-http/.changes/next-release/smithy-http-enhancement-20251122132342.json
@@ -0,0 +1,4 @@
+{
+  "type": "enhancement",
+  "description": "Improved error messaging for CRT-based timeout errors."
+}
\ No newline at end of file
diff --git a/packages/smithy-http/src/smithy_http/aio/crt.py b/packages/smithy-http/src/smithy_http/aio/crt.py
index db13162e1..5e5cc861c 100644
--- a/packages/smithy-http/src/smithy_http/aio/crt.py
+++ b/packages/smithy-http/src/smithy_http/aio/crt.py
@@ -187,7 +187,7 @@ async def send(
             return await self._await_response(crt_stream)
         except AwsCrtError as e:
             if e.name in self._TIMEOUT_ERROR_NAMES:
-                raise _CRTTimeoutError() from e
+                raise _CRTTimeoutError(f"CRT {e.name}: {e.message}") from e
             raise
 
     async def _await_response(