diff --git a/crates/dbx-mcp/src/server.rs b/crates/dbx-mcp/src/server.rs
index b687b5d37c..43af42b684 100644
--- a/crates/dbx-mcp/src/server.rs
+++ b/crates/dbx-mcp/src/server.rs
@@ -55,6 +55,7 @@ enum DbxResourceRequest {
 }
 
 #[derive(Debug, Deserialize, schemars::JsonSchema)]
+#[schemars(extend("properties" = {}))]
 pub struct ListConnectionsRequest {}
 
 #[derive(Debug, Deserialize, schemars::JsonSchema)]
@@ -3371,6 +3372,9 @@ impl DbxMcpServer {
         if self.plugin_tools_mode.advertise_flat() {
             tools.extend(self.plugin_tools_view(policy.as_ref()).await);
         }
+        for tool in &mut tools {
+            normalize_tool_input_schema(tool);
+        }
         tools
     }
 
@@ -4003,6 +4007,23 @@ impl ServerHandler for DbxMcpServer {
     }
 }
 
+/// Ensure object-typed input schemas publish a `properties` object.
+/// OpenAI-compatible gateways (e.g. DashScope / 通义千问, DeepSeek Harness)
+/// strictly validate tool schemas and reject all tool calls if any tool
+/// with `type: "object"` lacks a `properties` map (issue #12464).
+fn normalize_tool_input_schema(tool: &mut rmcp::model::Tool) {
+    let is_object = match tool.input_schema.get("type") {
+        Some(serde_json::Value::String(t)) => t == "object",
+        None => true,
+        _ => false,
+    };
+    if is_object && !tool.input_schema.contains_key("properties") {
+        let mut object = (*tool.input_schema).clone();
+        object.insert("properties".to_string(), serde_json::json!({}));
+        tool.input_schema = std::sync::Arc::new(object);
+    }
+}
+
 fn parse_dbx_resource_uri(uri: &str) -> Result<DbxResourceRequest, ErrorData> {
     let parsed = Url::parse(uri).map_err(|_| ErrorData::invalid_params("Invalid DBX resource URI.", None))?;
     if parsed.scheme() != "dbx"
@@ -6628,6 +6649,58 @@ mod tests {
             .is_some_and(|required| required.iter().any(|field| field == "tables")));
     }
 
+    #[test]
+    fn all_advertised_tools_publish_properties_in_input_schema() {
+        let server = DbxMcpServer::with_runtime_options(Arc::new(FakeBackend::default()), McpScope::default(), false);
+        let tools = server.tool_router.list_all();
+
+        for tool in &tools {
+            let is_object = match tool.input_schema.get("type") {
+                Some(serde_json::Value::String(t)) => t == "object",
+                None => true,
+                _ => false,
+            };
+            if is_object {
+                assert!(
+                    tool.input_schema.get("properties").and_then(serde_json::Value::as_object).is_some(),
+                    "tool {} inputSchema must publish a 'properties' object for OpenAI compatibility (issue #12464)",
+                    tool.name
+                );
+            }
+        }
+
+        let list_connections = tools
+            .iter()
+            .find(|tool| tool.name == "dbx_list_connections")
+            .expect("dbx_list_connections should be registered");
+        assert_eq!(
+            list_connections.input_schema.get("properties"),
+            Some(&serde_json::json!({})),
+            "dbx_list_connections must have empty properties object"
+        );
+    }
+
+    #[tokio::test]
+    async fn policy_filtered_tools_guarantee_properties_for_all_object_schemas() {
+        let server = DbxMcpServer::with_runtime_options(Arc::new(FakeBackend::default()), McpScope::default(), false);
+        let tools = server.policy_filtered_tools().await;
+
+        for tool in &tools {
+            let is_object = match tool.input_schema.get("type") {
+                Some(serde_json::Value::String(t)) => t == "object",
+                None => true,
+                _ => false,
+            };
+            if is_object {
+                assert!(
+                    tool.input_schema.get("properties").and_then(serde_json::Value::as_object).is_some(),
+                    "advertised tool {} inputSchema must publish 'properties'",
+                    tool.name
+                );
+            }
+        }
+    }
+
     #[test]
     fn connection_selector_schema_uses_optional_strings() {
         let server = DbxMcpServer::with_runtime_options(Arc::new(FakeBackend::default()), McpScope::default(), false);