fix(mcp): default tool schema properties (#32568)

packages/opencode/src/session/tools.ts

@@ -119,7 +119,7 @@ export const resolve = Effect.fn("SessionTools.resolve")(function* (input: {
     if (!execute) continue
 
     const schema = yield* Effect.promise(() => Promise.resolve(asSchema(item.inputSchema).jsonSchema))
-    const transformed = ProviderTransform.schema(input.model, schema)
+    const transformed = ProviderTransform.schema(input.model, { ...schema, properties: schema.properties ?? {} })
     item.inputSchema = jsonSchema(transformed)
     item.execute = (args, opts) =>
       run.promise(