diff --git a/lib/permissions/minimally-encoded-thread-permissions.js b/lib/permissions/minimally-encoded-thread-permissions.js
--- a/lib/permissions/minimally-encoded-thread-permissions.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.js
@@ -1,6 +1,7 @@
 // @flow
 
 import invariant from 'invariant';
+import t, { type TInterface } from 'tcomb';
 
 import { parseThreadPermissionString } from './prefixes.js';
 import type {
@@ -8,7 +9,11 @@
   ThreadPermissionsInfo,
   ThreadRolePermissionsBlob,
 } from '../types/thread-permission-types.js';
+import type { RoleInfo } from '../types/thread-types.js';
+import { roleInfoValidator } from '../types/thread-types.js';
 import { entries, invertObjectToMap } from '../utils/objects.js';
+import { tRegex, tShape } from '../utils/validation-utils.js';
+import type { TRegex } from '../utils/validation-utils.js';
 
 // `baseRolePermissionEncoding` maps permission names to indices.
 // These indices represent the 6-bit basePermission part of the 10-bit role
@@ -179,6 +184,18 @@
     ]),
   );
 
+export type MinimallyEncodedRoleInfo = {
+  ...RoleInfo,
+  +permissions: $ReadOnlyArray<string>,
+};
+
+const tHexEncodedRolePermission: TRegex = tRegex(/^[0-9a-fA-F]{3,}$/);
+const minimallyEncodedRoleInfoValidator: TInterface<MinimallyEncodedRoleInfo> =
+  tShape<MinimallyEncodedRoleInfo>({
+    ...roleInfoValidator.meta.props,
+    permissions: t.list(tHexEncodedRolePermission),
+  });
+
 export {
   permissionsToBitmaskHex,
   hasPermission,
@@ -186,4 +203,5 @@
   decodeRolePermissionBitmask,
   threadRolePermissionsBlobToBitmaskArray,
   decodeThreadRolePermissionsBitmaskArray,
+  minimallyEncodedRoleInfoValidator,
 };
diff --git a/lib/permissions/minimally-encoded-thread-permissions.test.js b/lib/permissions/minimally-encoded-thread-permissions.test.js
--- a/lib/permissions/minimally-encoded-thread-permissions.test.js
+++ b/lib/permissions/minimally-encoded-thread-permissions.test.js
@@ -4,6 +4,7 @@
   decodeRolePermissionBitmask,
   decodeThreadRolePermissionsBitmaskArray,
   hasPermission,
+  minimallyEncodedRoleInfoValidator,
   permissionsToBitmaskHex,
   rolePermissionToBitmaskHex,
   threadRolePermissionsBlobToBitmaskArray,
@@ -221,3 +222,63 @@
     ).toEqual(threadRolePermissionsBlob);
   });
 });
+
+describe('minimallyEncodedRoleInfoValidator', () => {
+  it('should validate correctly formed MinimallyEncodedRoleInfo', () => {
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 'roleID',
+        name: 'roleName',
+        permissions: ['abc', 'def'],
+        isDefault: true,
+      }),
+    ).toBe(true);
+  });
+
+  it('should NOT validate malformed MinimallyEncodedRoleInfo', () => {
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 1234,
+        name: 'roleName',
+        permissions: ['abc', 'def'],
+        isDefault: true,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 'roleID',
+        name: 'roleName',
+        permissions: ['hello a02 test', 'def'],
+        isDefault: true,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 'roleID',
+        name: 'roleName',
+        permissions: [123, 456],
+        isDefault: true,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 'roleID',
+        name: 'roleName',
+        permissions: ['ZZZ', 'YYY'],
+        isDefault: true,
+      }),
+    ).toBe(false);
+
+    expect(
+      minimallyEncodedRoleInfoValidator.is({
+        id: 'roleID',
+        name: 'roleName',
+        permissions: ['AAAAA', 'YYY'],
+        isDefault: true,
+      }),
+    ).toBe(false);
+  });
+});
diff --git a/lib/types/thread-types.js b/lib/types/thread-types.js
--- a/lib/types/thread-types.js
+++ b/lib/types/thread-types.js
@@ -65,7 +65,7 @@
   +permissions: ThreadRolePermissionsBlob,
   +isDefault: boolean,
 };
-const roleInfoValidator = tShape<RoleInfo>({
+export const roleInfoValidator: TInterface<RoleInfo> = tShape<RoleInfo>({
   id: tID,
   name: t.String,
   permissions: threadRolePermissionsBlobValidator,
diff --git a/lib/utils/validation-utils.js b/lib/utils/validation-utils.js
--- a/lib/utils/validation-utils.js
+++ b/lib/utils/validation-utils.js
@@ -40,7 +40,7 @@
   return t.interface(spec, { strict: true });
 }
 
-type TRegex = TRefinement<string>;
+export type TRegex = TRefinement<string>;
 function tRegex(regex: RegExp): TRegex {
   return t.refinement(t.String, val => regex.test(val));
 }