[elicitations] Switch to use MCP style elicitation payload for mcp tool approvals. (#13621)

- [x] Switch to use MCP style elicitation payload for mcp tool
approvals.
- [ ] TODO: Update the UI to support the full spec.

codex-rs/core/src/features.rs

@@ -147,6 +147,8 @@ pub enum Feature {
     /// Enable collaboration modes (Plan, Default).
     /// Kept for config backward compatibility; behavior is always collaboration-modes-enabled.
     CollaborationModes,
+    /// Route MCP tool approval prompts through the MCP elicitation request path.
+    ToolCallMcpElicitation,
     /// Enable personality selection in the TUI.
     Personality,
     /// Enable native artifact tools.
@@ -693,6 +695,12 @@ pub const FEATURES: &[FeatureSpec] = &[
         stage: Stage::Removed,
         default_enabled: true,
     },
+    FeatureSpec {
+        id: Feature::ToolCallMcpElicitation,
+        key: "tool_call_mcp_elicitation",
+        stage: Stage::UnderDevelopment,
+        default_enabled: false,
+    },
     FeatureSpec {
         id: Feature::Personality,
         key: "personality",