diff --git a/packages/opencode/src/config/provider.ts b/packages/opencode/src/config/provider.ts
index 5635512ced..a9432f1226 100644
--- a/packages/opencode/src/config/provider.ts
+++ b/packages/opencode/src/config/provider.ts
@@ -44,8 +44,8 @@ export const Model = Schema.Struct({
   ),
   modalities: Schema.optional(
     Schema.Struct({
-      input: Schema.mutable(Schema.Array(Schema.Literals(["text", "audio", "image", "video", "pdf"]))),
-      output: Schema.mutable(Schema.Array(Schema.Literals(["text", "audio", "image", "video", "pdf"]))),
+      input: Schema.optional(Schema.mutable(Schema.Array(Schema.Literals(["text", "audio", "image", "video", "pdf"])))),
+      output: Schema.optional(Schema.mutable(Schema.Array(Schema.Literals(["text", "audio", "image", "video", "pdf"])))),
     }),
   ),
   experimental: Schema.optional(Schema.Boolean),