[mcp] Improve custom MCP elicitation (#15800)

- [x] Support don't ask again for custom MCP tool calls.
- [x] Don't run arc in yolo mode.
- [x] Run arc for custom MCP tools in always allow mode.

codex-rs/core/config.schema.json

@@ -745,6 +745,21 @@
         }
       ]
     },
+    "McpServerToolConfig": {
+      "additionalProperties": false,
+      "description": "Per-tool approval settings for a single MCP server tool.",
+      "properties": {
+        "approval_mode": {
+          "allOf": [
+            {
+              "$ref": "#/definitions/AppToolApproval"
+            }
+          ],
+          "description": "Approval mode for this tool."
+        }
+      },
+      "type": "object"
+    },
     "MemoriesToml": {
       "additionalProperties": false,
       "description": "Memories settings loaded from config.toml.",
@@ -1246,7 +1261,9 @@
       "type": "object"
     },
     "RawMcpServerConfig": {
-      "additionalProperties": false,
+      "additionalProperties": {
+        "$ref": "#/definitions/McpServerToolConfig"
+      },
       "properties": {
         "args": {
           "default": null,
@@ -1313,6 +1330,11 @@
           },
           "type": "object"
         },
+        "name": {
+          "default": null,
+          "description": "Legacy display-name field accepted for backward compatibility.",
+          "type": "string"
+        },
         "oauth_resource": {
           "default": null,
           "type": "string"
@@ -1344,6 +1366,13 @@
           "format": "double",
           "type": "number"
         },
+        "tools": {
+          "additionalProperties": {
+            "$ref": "#/definitions/McpServerToolConfig"
+          },
+          "default": null,
+          "type": "object"
+        },
         "url": {
           "type": "string"
         }