Omit the required key when schema projection empties it

Author: RhysSullivan

packages/plugins/apps/src/plugin/apps-plugin.test.ts

@@ -256,8 +256,12 @@ describe("apps plugin schema projection", () => {
             },
           },
         },
-        required: undefined,
       });
+      // The response schema requires JSON values: a `required` key holding
+      // undefined fails encoding (the /api/tools/schema 400), so the key must
+      // be absent entirely when all required fields were projected away.
+      expect("required" in (result.inputSchema as Record<string, unknown>)).toBe(false);
+      expect(JSON.parse(JSON.stringify(result.inputSchema))).toEqual(result.inputSchema);
     }),
   );
 });

packages/plugins/apps/src/plugin/apps-plugin.ts

@@ -564,11 +564,14 @@ export const projectAppsToolSchema = (
     const required = Array.isArray(schema.required)
       ? schema.required.filter((field) => !projectedFields.has(String(field)))
       : undefined;
+    // Rebuild without the `required` key rather than setting it to undefined:
+    // an explicit undefined is not a JSON value and fails response encoding.
+    const { required: _dropped, ...rest } = schema;
     return {
       inputSchema: {
-        ...schema,
+        ...rest,
         properties,
-        ...(required && required.length > 0 ? { required } : { required: undefined }),
+        ...(required && required.length > 0 ? { required } : {}),
       },
       outputSchema,
     };