test

codex-rs/core/src/tools/spec_tests.rs

@@ -19,6 +19,8 @@ use codex_protocol::protocol::SessionSource;
 use codex_tools::AdditionalProperties;
 use codex_tools::DiscoverableTool;
 use codex_tools::JsonSchema;
+use codex_tools::JsonSchemaPrimitiveType;
+use codex_tools::JsonSchemaType;
 use codex_tools::LoadableToolSpec;
 use codex_tools::REQUEST_PLUGIN_INSTALL_TOOL_NAME;
 use codex_tools::ResponsesApiNamespaceTool;
@@ -1139,7 +1141,7 @@ async fn unavailable_mcp_tools_are_exposed_as_dummy_function_tools() {
 }
 
 #[tokio::test]
-async fn test_mcp_tool_property_missing_type_defaults_to_string() {
+async fn test_mcp_tool_property_missing_type_defaults_to_open_object() {
     let config = test_config().await;
     let model_info = construct_model_info_offline("gpt-5.4", &config);
     let mut features = Features::with_defaults();
@@ -1185,7 +1187,13 @@ async fn test_mcp_tool_property_missing_type_defaults_to_string() {
                 /*properties*/
                 BTreeMap::from([(
                     "query".to_string(),
-                    JsonSchema::string(Some("search query".to_string())),
+                    JsonSchema {
+                        schema_type: Some(JsonSchemaType::Single(JsonSchemaPrimitiveType::Object)),
+                        description: Some("search query".to_string()),
+                        properties: Some(BTreeMap::new()),
+                        additional_properties: Some(true.into()),
+                        ..Default::default()
+                    },
                 )]),
                 /*required*/ None,
                 /*additional_properties*/ None

codex-rs/tools/src/dynamic_tool_tests.rs

@@ -29,7 +29,15 @@ fn parse_dynamic_tool_sanitizes_input_schema() {
             input_schema: JsonSchema::object(
                 BTreeMap::from([(
                     "id".to_string(),
-                    JsonSchema::string(Some("Ticket identifier".to_string()),),
+                    JsonSchema {
+                        schema_type: Some(crate::JsonSchemaType::Single(
+                            crate::JsonSchemaPrimitiveType::Object,
+                        )),
+                        description: Some("Ticket identifier".to_string()),
+                        properties: Some(BTreeMap::new()),
+                        additional_properties: Some(true.into()),
+                        ..Default::default()
+                    },
                 )]),
                 /*required*/ None,
                 /*additional_properties*/ None

codex-rs/tools/src/json_schema.rs

@@ -228,7 +228,10 @@ fn sanitize_json_schema(value: &mut JsonValue) {
                 {
                     schema_types.push(JsonSchemaPrimitiveType::Number);
                 } else {
-                    schema_types.push(JsonSchemaPrimitiveType::String);
+                    // With no schema hints, fall back to an open object so unknown
+                    // tool argument shapes can still carry arbitrary named fields.
+                    schema_types.push(JsonSchemaPrimitiveType::Object);
+                    map.insert("additionalProperties".to_string(), JsonValue::Bool(true));
                 }
             }
 

codex-rs/tools/src/json_schema_tests.rs

@@ -34,7 +34,7 @@ fn parse_tool_input_schema_infers_object_shape_and_defaults_properties() {
     //
     // Expected normalization behavior:
     // - `properties` implies an object schema when `type` is omitted.
-    // - The child property keeps its description and defaults to a string type.
+    // - The child property keeps its description and defaults to an open object.
     let schema = parse_tool_input_schema(&serde_json::json!({
         "properties": {
             "query": {"description": "search query"}
@@ -47,7 +47,13 @@ fn parse_tool_input_schema_infers_object_shape_and_defaults_properties() {
         JsonSchema::object(
             BTreeMap::from([(
                 "query".to_string(),
-                JsonSchema::string(Some("search query".to_string())),
+                JsonSchema {
+                    schema_type: Some(JsonSchemaType::Single(JsonSchemaPrimitiveType::Object)),
+                    description: Some("search query".to_string()),
+                    properties: Some(BTreeMap::new()),
+                    additional_properties: Some(true.into()),
+                    ..Default::default()
+                },
             )]),
             /*required*/ None,
             /*additional_properties*/ None
@@ -250,16 +256,73 @@ fn parse_tool_input_schema_infers_string_from_enum_const_and_format_keywords() {
 }
 
 #[test]
-fn parse_tool_input_schema_defaults_empty_schema_to_string() {
+fn parse_tool_input_schema_defaults_empty_schema_to_open_object() {
     // Example schema shape:
     // {}
     //
     // Expected normalization behavior:
     // - With no structural hints at all, the normalizer falls back to a
-    //   permissive string schema.
+    //   permissive object schema.
     let schema = parse_tool_input_schema(&serde_json::json!({})).expect("parse schema");
 
-    assert_eq!(schema, JsonSchema::string(/*description*/ None));
+    assert_eq!(
+        schema,
+        JsonSchema::object(BTreeMap::new(), /*required*/ None, Some(true.into()))
+    );
+}
+
+#[test]
+fn parse_tool_input_schema_defaults_nested_empty_schema_to_open_object() {
+    // Example schema shape:
+    // {
+    //   "type": "object",
+    //   "properties": {
+    //     "metadata": {
+    //       "properties": {
+    //         "extra": {}
+    //       }
+    //     }
+    //   }
+    // }
+    //
+    // Expected normalization behavior:
+    // - The sanitizer recurses through nested object properties.
+    // - The innermost `extra` field has no hints, so it falls back to an open
+    //   object.
+    let schema = parse_tool_input_schema(&serde_json::json!({
+        "type": "object",
+        "properties": {
+            "metadata": {
+                "properties": {
+                    "extra": {}
+                }
+            }
+        }
+    }))
+    .expect("parse schema");
+
+    assert_eq!(
+        schema,
+        JsonSchema::object(
+            BTreeMap::from([(
+                "metadata".to_string(),
+                JsonSchema::object(
+                    BTreeMap::from([(
+                        "extra".to_string(),
+                        JsonSchema::object(
+                            BTreeMap::new(),
+                            /*required*/ None,
+                            Some(true.into()),
+                        ),
+                    )]),
+                    /*required*/ None,
+                    /*additional_properties*/ None,
+                )
+            )]),
+            /*required*/ None,
+            /*additional_properties*/ None,
+        )
+    );
 }
 
 #[test]