diff --git a/open-sse/translator/formats/gemini.js b/open-sse/translator/formats/gemini.js
index b1d4db34..6393a78b 100644
--- a/open-sse/translator/formats/gemini.js
+++ b/open-sse/translator/formats/gemini.js
@@ -7,7 +7,13 @@ import { OPENAI_BLOCK } from "../schema/index.js";
 export const UNSUPPORTED_SCHEMA_CONSTRAINTS = [
   // Basic constraints (not supported by Gemini API)
   "minLength", "maxLength", "exclusiveMinimum", "exclusiveMaximum",
-  "minItems", "maxItems", "format",
+  "minItems", "maxItems", "format", "multipleOf",
+  // Array keywords the Gemini schema proto has no field for. Agent tool
+  // schemas set these routinely, and one occurrence rejects the whole request
+  // with "Unknown name ...: Cannot find field".
+  "uniqueItems", "contains",
+  // 2020-12 keywords with no Gemini equivalent
+  "unevaluatedProperties", "unevaluatedItems", "contentSchema",
   // Claude rejects these in VALIDATED mode
   "default", "examples",
   // JSON Schema meta keywords