diff --git a/lib/ruby_llm/schema.rb b/lib/ruby_llm/schema.rb
index 65d12a4..cac5603 100644
--- a/lib/ruby_llm/schema.rb
+++ b/lib/ruby_llm/schema.rb
@@ -51,11 +51,12 @@ def additional_properties(value = nil)
         @additional_properties = value
       end
 
-      def strict(value = nil)
-        if value.nil?
-          return @strict.nil? ? (@strict = true) : @strict
+      def strict(*args)
+        if args.empty?
+          instance_variable_defined?(:@strict) ? @strict : true
+        else
+          @strict = args.first
         end
-        @strict = value
       end
 
       def validate!
diff --git a/lib/ruby_llm/schema/json_output.rb b/lib/ruby_llm/schema/json_output.rb
index baf40a5..0fb57a7 100644
--- a/lib/ruby_llm/schema/json_output.rb
+++ b/lib/ruby_llm/schema/json_output.rb
@@ -10,10 +10,11 @@ def to_json_schema
           type: "object",
           properties: self.class.properties,
           required: self.class.required_properties,
-          additionalProperties: self.class.additional_properties,
-          strict: self.class.strict
+          additionalProperties: self.class.additional_properties
         }
 
+        schema_hash[:strict] = self.class.strict unless self.class.strict.nil?
+
         # Only include $defs if there are definitions
         schema_hash["$defs"] = self.class.definitions unless self.class.definitions.empty?
 
diff --git a/spec/ruby_llm/schema/strict_spec.rb b/spec/ruby_llm/schema/strict_spec.rb
new file mode 100644
index 0000000..1cbf5eb
--- /dev/null
+++ b/spec/ruby_llm/schema/strict_spec.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+require "spec_helper"
+
+RSpec.describe RubyLLM::Schema, ".strict" do
+  it "outputs strict: true by default" do
+    schema = Class.new(RubyLLM::Schema)
+    output = schema.new.to_json_schema
+    expect(output[:schema][:strict]).to eq(true)
+  end
+
+  it "omits strict from output when set to nil" do
+    schema = Class.new(RubyLLM::Schema) { strict nil }
+    output = schema.new.to_json_schema
+    expect(output[:schema]).not_to have_key(:strict)
+  end
+
+  it "outputs strict: true when set to true" do
+    schema = Class.new(RubyLLM::Schema) { strict true }
+    output = schema.new.to_json_schema
+    expect(output[:schema][:strict]).to eq(true)
+  end
+
+  it "outputs strict: false when set to false" do
+    schema = Class.new(RubyLLM::Schema) { strict false }
+    output = schema.new.to_json_schema
+    expect(output[:schema][:strict]).to eq(false)
+  end
+end