[router] Add multi-turn tool calling loop support for MCP integration (#11143)

sgl-router/src/protocols/spec.rs

@@ -723,7 +723,10 @@ pub enum ResponseToolType {
 #[derive(Debug, Clone, Deserialize, Serialize)]
 pub struct ResponseReasoningParam {
     #[serde(default = "default_reasoning_effort")]
+    #[serde(skip_serializing_if = "Option::is_none")]
     pub effort: Option<ReasoningEffort>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub summary: Option<ReasoningSummary>,
 }
 
 fn default_reasoning_effort() -> Option<ReasoningEffort> {
@@ -738,6 +741,14 @@ pub enum ReasoningEffort {
     High,
 }
 
+#[derive(Debug, Clone, Deserialize, Serialize)]
+#[serde(rename_all = "snake_case")]
+pub enum ReasoningSummary {
+    Auto,
+    Concise,
+    Detailed,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize)]
 #[serde(tag = "type")]
 #[serde(rename_all = "snake_case")]