diff --git a/src/time/src/mcp_server_time/server.py b/src/time/src/mcp_server_time/server.py
index 83e97af333..2fe861dbd3 100644
--- a/src/time/src/mcp_server_time/server.py
+++ b/src/time/src/mcp_server_time/server.py
@@ -131,7 +131,7 @@ async def list_tools() -> list[Tool]:
         return [
             Tool(
                 name=TimeTools.GET_CURRENT_TIME.value,
-                description="Get current time in a specific timezones",
+                description="Get current time in a specific timezone",
                 inputSchema={
                     "type": "object",
                     "properties": {
@@ -212,6 +212,8 @@ async def call_tool(
                 TextContent(type="text", text=json.dumps(result.model_dump(), indent=2))
             ]
 
+        except McpError:
+            raise
         except Exception as e:
             raise ValueError(f"Error processing mcp-server-time query: {str(e)}")
 
diff --git a/src/time/test/time_server_test.py b/src/time/test/time_server_test.py
index 8d963508d7..3a506505f9 100644
--- a/src/time/test/time_server_test.py
+++ b/src/time/test/time_server_test.py
@@ -526,3 +526,34 @@ def test_get_local_tz_various_timezones(mock_get_localzone, timezone_name):
     result = get_local_tz()
     assert str(result) == timezone_name
     assert isinstance(result, ZoneInfo)
+
+
+def test_get_current_time_invalid_timezone_raises_invalid_params():
+    """McpError for an unknown timezone must carry the INVALID_PARAMS error code.
+
+    This guards against the call_tool handler accidentally catching McpError and
+    re-raising it as a plain ValueError (which loses the structured error code).
+    """
+    from mcp.types import INVALID_PARAMS as MCP_INVALID_PARAMS
+    time_server = TimeServer()
+    with pytest.raises(McpError) as exc_info:
+        time_server.get_current_time("Bad/Timezone")
+    assert exc_info.value.error.code == MCP_INVALID_PARAMS
+
+
+def test_convert_time_invalid_source_timezone_raises_invalid_params():
+    """McpError for an invalid source timezone must carry the INVALID_PARAMS error code."""
+    from mcp.types import INVALID_PARAMS as MCP_INVALID_PARAMS
+    time_server = TimeServer()
+    with pytest.raises(McpError) as exc_info:
+        time_server.convert_time("Bad/Source", "12:00", "Europe/London")
+    assert exc_info.value.error.code == MCP_INVALID_PARAMS
+
+
+def test_convert_time_invalid_target_timezone_raises_invalid_params():
+    """McpError for an invalid target timezone must carry the INVALID_PARAMS error code."""
+    from mcp.types import INVALID_PARAMS as MCP_INVALID_PARAMS
+    time_server = TimeServer()
+    with pytest.raises(McpError) as exc_info:
+        time_server.convert_time("Europe/London", "12:00", "Bad/Target")
+    assert exc_info.value.error.code == MCP_INVALID_PARAMS