fix: transform MCP tool schemas for Google/Gemini compatibility (#4538)

Co-authored-by: Aiden Cline <aidenpcline@gmail.com>
Co-authored-by: Github Action <action@github.com>
Co-authored-by: Aiden Cline <63023139+rekram1-node@users.noreply.github.com>

packages/opencode/src/provider/transform.ts

@@ -254,7 +254,7 @@ export namespace ProviderTransform {
     return standardLimit
   }
 
-  export function schema(_providerID: string, _modelID: string, schema: JSONSchema.BaseSchema) {
+  export function schema(providerID: string, modelID: string, schema: JSONSchema.BaseSchema) {
     /*
     if (["openai", "azure"].includes(providerID)) {
       if (schema.type === "object" && schema.properties) {
@@ -271,11 +271,40 @@ export namespace ProviderTransform {
         }
       }
     }
-
-    if (providerID === "google") {
-    }
     */
 
+    // Convert integer enums to string enums for Google/Gemini
+    if (providerID === "google" || modelID.includes("gemini")) {
+      const convertIntEnumsToStrings = (obj: any): any => {
+        if (obj === null || typeof obj !== "object") {
+          return obj
+        }
+
+        if (Array.isArray(obj)) {
+          return obj.map(convertIntEnumsToStrings)
+        }
+
+        const result: any = {}
+        for (const [key, value] of Object.entries(obj)) {
+          if (key === "enum" && Array.isArray(value)) {
+            // Convert all enum values to strings
+            result[key] = value.map((v) => String(v))
+            // If we have integer type with enum, change type to string
+            if (result.type === "integer" || result.type === "number") {
+              result.type = "string"
+            }
+          } else if (typeof value === "object" && value !== null) {
+            result[key] = convertIntEnumsToStrings(value)
+          } else {
+            result[key] = value
+          }
+        }
+        return result
+      }
+
+      schema = convertIntEnumsToStrings(schema)
+    }
+
     return schema
   }