diff --git a/examples/basic/previous-response-id.ts b/examples/basic/previous-response-id.ts
new file mode 100644
index 0000000..45e233f
--- /dev/null
+++ b/examples/basic/previous-response-id.ts
@@ -0,0 +1,95 @@
+import { Agent, Runner } from '../../src/agents';
+
+/**
+ * This demonstrates usage of the `previous_response_id` parameter to continue a conversation.
+ * The second run passes the previous response ID to the model, which allows it to continue the
+ * conversation without re-sending the previous messages.
+ *
+ * Notes:
+ * 1. This only applies to the OpenAI Responses API. Other models will ignore this parameter.
+ * 2. Responses are only stored for 30 days as of this writing, so in production you should
+ *    store the response ID along with an expiration date; if the response is no longer valid,
+ *    you'll need to re-send the previous conversation history.
+ */
+
+async function main() {
+  const agent = new Agent({
+    name: 'Assistant',
+    instructions: 'You are a helpful assistant. be VERY concise.',
+  });
+
+  const result = await Runner.run(
+    agent,
+    'What is the largest country in South America?'
+  );
+  console.log(result.finalOutput);
+  // Brazil
+  console.log('first message response_id:', result.lastResponseId);
+
+  const followupResult = await Runner.run(
+    agent,
+    'What is the capital of that country?',
+    { previousResponseId: result.lastResponseId! }
+  );
+  console.log(followupResult.finalOutput);
+  // Brasilia
+  console.log('second message response_id:', followupResult.lastResponseId);
+}
+
+async function mainStream() {
+  const agent = new Agent({
+    name: 'Assistant',
+    instructions: 'You are a helpful assistant. be VERY concise.',
+    tools: [],
+  });
+
+  const result = Runner.runStreamed(
+    agent,
+    'What is the largest country in South America?'
+  );
+
+  for await (const event of result.streamEvents()) {
+    if (
+      event.type === 'raw_response_event' &&
+      event.data.type === 'response.output_text.delta'
+    ) {
+      process.stdout.write(event.data.delta);
+    }
+  }
+  console.log('\n---');
+
+  console.log('first messageresponse_id:', result.lastResponseId);
+
+  const followupResult = Runner.runStreamed(
+    agent,
+    'What is the capital of that country?',
+    { previousResponseId: result.lastResponseId! }
+  );
+
+  for await (const event of followupResult.streamEvents()) {
+    if (
+      event.type === 'raw_response_event' &&
+      event.data.type === 'response.output_text.delta'
+    ) {
+      process.stdout.write(event.data.delta);
+    }
+  }
+
+  console.log('\n---');
+  console.log('second message response_id:', followupResult.lastResponseId);
+}
+
+// Get user input for stream mode
+const readline = require('readline').createInterface({
+  input: process.stdin,
+  output: process.stdout,
+});
+
+readline.question('Run in stream mode? (y/n): ', (answer: string) => {
+  readline.close();
+  if (answer.toLowerCase() === 'y') {
+    mainStream();
+  } else {
+    main();
+  }
+});
diff --git a/package.json b/package.json
index d9b4cc3..4cdd95d 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "openai-agents-js",
-  "version": "0.1.2",
+  "version": "0.1.4",
   "description": "An unofficial Node.js library for building AI agents and multi-agent workflows with OpenAI",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",
diff --git a/src/agents/agent/index.ts b/src/agents/agent/index.ts
index 92ba705..c215216 100644
--- a/src/agents/agent/index.ts
+++ b/src/agents/agent/index.ts
@@ -74,7 +74,7 @@ interface AgentProps<TContext = any> {
   /** Model-specific tuning parameters */
   model_settings?: ModelSettings;
   /** A list of tools that the agent can use */
-  tools: Array<Tool>;
+  tools?: Array<Tool>;
   /** Model Context Protocol servers the agent can use */
   mcp_servers?: any; // TODO: Implement `MCPServer` . Then uncomment: Array<MCPServer>
   /** Checks that run before generating a response */
@@ -126,7 +126,7 @@ export class Agent<TContext> {
   model_settings: ModelSettings = new ModelSettings();
 
   /** A list of tools that the agent can use */
-  tools: Array<Tool> = [];
+  tools?: Array<Tool> = [];
 
   /**
    * A list of Model Context Protocol servers that the agent can use.
@@ -188,7 +188,7 @@ export class Agent<TContext> {
     this.handoffs = handoffs;
     this.model = model ?? DEFAULT_MODEL;
     this.model_settings = model_settings ?? new ModelSettings();
-    this.tools = tools;
+    this.tools = tools || [];
     this.mcp_servers = mcp_servers;
     this.input_guardrails = input_guardrails ?? [];
     this.output_guardrails = output_guardrails ?? [];
@@ -229,7 +229,7 @@ export class Agent<TContext> {
    */
   async getAllTools(): Promise<Tool[]> {
     const mcpTools = await this.getMCPTools();
-    return [...mcpTools, ...this.tools];
+    return [...(mcpTools ?? []), ...(this.tools ?? [])];
   }
 
   /**
diff --git a/src/agents/items/index.ts b/src/agents/items/index.ts
index 38c4117..dbb9da6 100644
--- a/src/agents/items/index.ts
+++ b/src/agents/items/index.ts
@@ -239,16 +239,16 @@ export class ModelResponse {
    * An ID for the response which can be used to refer to the response in subsequent calls to the
    * model. Not supported by all model providers.
    */
-  referenceable_id: string | null;
+  response_id: string | null;
 
   constructor(
     output: TResponseOutputItem[],
     usage: Usage,
-    referenceable_id: string | null = null
+    response_id: string | null = null
   ) {
     this.output = output;
     this.usage = usage;
-    this.referenceable_id = referenceable_id;
+    this.response_id = response_id;
   }
 
   /**
diff --git a/src/agents/models/interface.ts b/src/agents/models/interface.ts
index e70aa96..aeea3ce 100644
--- a/src/agents/models/interface.ts
+++ b/src/agents/models/interface.ts
@@ -71,7 +71,8 @@ export abstract class Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): Promise<ModelResponse>;
 
   /**
@@ -93,7 +94,8 @@ export abstract class Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): AsyncIterableIterator<TResponseStreamEvent>;
 }
 
diff --git a/src/agents/models/openai-chatcompletions.ts b/src/agents/models/openai-chatcompletions.ts
index acf55c1..94120ee 100644
--- a/src/agents/models/openai-chatcompletions.ts
+++ b/src/agents/models/openai-chatcompletions.ts
@@ -87,7 +87,8 @@ export class OpenAIChatCompletionsModel implements Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): Promise<ModelResponse> {
     const convertedInput =
       typeof input === 'string'
@@ -160,7 +161,8 @@ export class OpenAIChatCompletionsModel implements Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): AsyncGenerator<TResponseStreamEvent> {
     const convertedInput =
       typeof input === 'string'
diff --git a/src/agents/models/openai-responses.ts b/src/agents/models/openai-responses.ts
index 11aee62..9310257 100644
--- a/src/agents/models/openai-responses.ts
+++ b/src/agents/models/openai-responses.ts
@@ -214,7 +214,8 @@ export class OpenAIResponsesModel implements Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): Promise<ModelResponse> {
     try {
       const response = await this.fetchResponse(
@@ -224,7 +225,8 @@ export class OpenAIResponsesModel implements Model {
         tools,
         outputSchema,
         handoffs,
-        false
+        false,
+        previousResponseId
       );
 
       if (!('usage' in response) || !response.usage) {
@@ -268,7 +270,8 @@ export class OpenAIResponsesModel implements Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    tracing: ModelTracing
+    tracing: ModelTracing,
+    previousResponseId?: string
   ): AsyncIterableIterator<TResponseStreamEvent> {
     const stream = await this.fetchResponse(
       systemInstructions,
@@ -277,7 +280,8 @@ export class OpenAIResponsesModel implements Model {
       tools,
       outputSchema,
       handoffs,
-      true
+      true,
+      previousResponseId
     );
 
     if (!(stream instanceof Stream)) {
@@ -296,7 +300,8 @@ export class OpenAIResponsesModel implements Model {
     tools: Tool[],
     outputSchema: AgentOutputSchema | null,
     handoffs: Handoff<any>[],
-    stream: boolean
+    stream: boolean,
+    previousResponseId?: string
   ): Promise<Response | Stream<ResponseStreamEvent>> {
     const listInput = Array.isArray(input)
       ? input
@@ -337,6 +342,7 @@ export class OpenAIResponsesModel implements Model {
       text: responseFormat,
       store: modelSettings.store ?? undefined,
       reasoning: modelSettings.reasoning ?? null,
+      previous_response_id: previousResponseId ?? undefined,
     };
 
     // console.log('----PARAMA SOKARIm\n\n', params, '\n\n----');
diff --git a/src/agents/result.ts b/src/agents/result.ts
index 1ed7374..6c832fa 100644
--- a/src/agents/result.ts
+++ b/src/agents/result.ts
@@ -112,6 +112,10 @@ export abstract class RunResultBase {
 
     return [...originalItems, ...newItems];
   }
+
+  get lastResponseId(): string | null {
+    return this.rawResponses[this.rawResponses.length - 1]?.response_id ?? null;
+  }
 }
 
 /**
diff --git a/src/agents/run.ts b/src/agents/run.ts
index 08baddc..70a86b8 100644
--- a/src/agents/run.ts
+++ b/src/agents/run.ts
@@ -116,20 +116,20 @@ export class RunConfig {
   /**
    * Whether tracing is disabled for the agent run. If disabled, we will not trace the agent run.
    */
-  tracingDisabled: boolean = false;
+  tracingDisabled?: boolean = false;
 
   /**
    * Whether we include potentially sensitive data (for example: inputs/outputs of tool calls or
    * LLM generations) in traces. If False, we'll still create spans for these events, but the
    * sensitive data will not be included.
    */
-  traceIncludeSensitiveData: boolean = true;
+  traceIncludeSensitiveData?: boolean = true;
 
   /**
    * The name of the run, used for tracing. Should be a logical name for the run, like
    * "Code generation workflow" or "Customer support agent".
    */
-  workflowName: string = 'Agent workflow';
+  workflowName?: string = 'Agent workflow';
 
   /**
    * A custom trace ID to use for tracing. If not provided, we will generate a new trace ID.
@@ -175,6 +175,7 @@ export class Runner {
       maxTurns?: number;
       hooks?: RunHooks<TContext>;
       runConfig?: RunConfig;
+      previousResponseId?: string;
     } = {}
   ): Promise<RunResult> {
     const {
@@ -191,7 +192,7 @@ export class Runner {
     const newTrace = currentTrace
       ? null
       : trace(
-          runConfig.workflowName,
+          runConfig.workflowName ?? 'Agent workflow',
           runConfig.traceId,
           runConfig.groupId,
           runConfig.traceMetadata,
@@ -286,6 +287,7 @@ export class Runner {
               runConfig,
               shouldRunAgentStartHooks,
               toolUseTracker,
+              previousResponseId: options.previousResponseId,
             });
           } else {
             // Fetch tools for subsequent turns if agent changed (span is new)
@@ -306,6 +308,7 @@ export class Runner {
               runConfig,
               shouldRunAgentStartHooks,
               toolUseTracker,
+              previousResponseId: options.previousResponseId,
             });
           }
           shouldRunAgentStartHooks = false;
@@ -444,6 +447,7 @@ export class Runner {
       maxTurns?: number;
       hooks?: RunHooks<TContext>;
       runConfig?: RunConfig;
+      previousResponseId?: string;
     } = {}
   ): RunResultStreaming {
     const {
@@ -458,7 +462,7 @@ export class Runner {
     const newTrace = currentTrace
       ? null
       : trace(
-          runConfig.workflowName,
+          runConfig.workflowName ?? 'Agent workflow',
           runConfig.traceId,
           runConfig.groupId,
           runConfig.traceMetadata,
@@ -495,7 +499,8 @@ export class Runner {
       maxTurns,
       hooks,
       contextWrapper,
-      runConfig
+      runConfig,
+      options.previousResponseId
     );
 
     // Set the task on the streamed result
@@ -717,6 +722,7 @@ export class Runner {
     runConfig,
     shouldRunAgentStartHooks,
     toolUseTracker,
+    previousResponseId,
   }: {
     agent: Agent<TContext>;
     allTools: Tool[];
@@ -727,6 +733,7 @@ export class Runner {
     runConfig: RunConfig;
     shouldRunAgentStartHooks: boolean;
     toolUseTracker: AgentToolUseTracker;
+    previousResponseId?: string;
   }): Promise<SingleStepResult> {
     // Ensure we run the hooks before anything else
     if (shouldRunAgentStartHooks) {
@@ -753,7 +760,8 @@ export class Runner {
       handoffs,
       contextWrapper,
       runConfig,
-      toolUseTracker
+      toolUseTracker,
+      previousResponseId
     );
 
     contextWrapper.usage.add(newResponse.usage);
@@ -786,7 +794,8 @@ export class Runner {
     handoffs: Handoff<any>[],
     contextWrapper: RunContextWrapper<any>,
     runConfig: RunConfig,
-    toolUseTracker: AgentToolUseTracker
+    toolUseTracker: AgentToolUseTracker,
+    previousResponseId?: string
   ): Promise<ModelResponse> {
     const model = Runner._getModel(agent, runConfig);
     const modelSettings = agent.model_settings.resolve(runConfig.modelSettings);
@@ -814,9 +823,10 @@ export class Runner {
       outputSchema,
       handoffs,
       getModelTracingImpl(
-        runConfig.tracingDisabled,
-        runConfig.traceIncludeSensitiveData
-      )
+        runConfig.tracingDisabled ?? false,
+        runConfig.traceIncludeSensitiveData ?? true
+      ),
+      previousResponseId
     );
 
     contextWrapper.usage.add(newResponse.usage);
@@ -890,7 +900,8 @@ export class Runner {
     maxTurns: number,
     hooks: RunHooks<TContext>,
     contextWrapper: RunContextWrapper<TContext>,
-    runConfig: RunConfig
+    runConfig: RunConfig,
+    previousResponseId?: string
   ): Promise<void> {
     const toolUseTracker = new AgentToolUseTracker();
     let currentAgent = startingAgent;
@@ -916,7 +927,6 @@ export class Runner {
       try {
         await streamedResult._input_guardrails_task; // Wait for guardrails before starting turns
       } catch (e) {
-        console.log(' OROSPO CUCU PATLMAA', e);
         if (e instanceof InputGuardrailTripwireTriggered) {
           // Error already logged and attached to span in _runInputGuardrails
           await streamedResult.setError(e); // Propagate error to stream consumer
@@ -996,7 +1006,8 @@ export class Runner {
             toolUseTracker,
             await Runner._getAllTools(currentAgent), // Pass current tools
             currentOriginalInput, // Pass input potentially modified by handoffs
-            currentGeneratedItems // Pass items accumulated so far
+            currentGeneratedItems, // Pass items accumulated so far
+            previousResponseId
           );
           shouldRunAgentStartHooks = false;
 
@@ -1261,7 +1272,8 @@ export class Runner {
     toolUseTracker: AgentToolUseTracker,
     allTools: Tool[],
     originalInput: string | TResponseInputItem[], // Receive current input state
-    preStepItems: RunItem[] // Receive items generated before this turn
+    preStepItems: RunItem[], // Receive items generated before this turn
+    previousResponseId?: string
   ): Promise<SingleStepResult> {
     // Returns the result after streaming completes
     if (shouldRunAgentStartHooks) {
@@ -1321,9 +1333,10 @@ export class Runner {
         outputSchema,
         handoffs,
         getModelTracingImpl(
-          runConfig.tracingDisabled,
-          runConfig.traceIncludeSensitiveData
-        )
+          runConfig.tracingDisabled ?? false,
+          runConfig.traceIncludeSensitiveData ?? true
+        ),
+        previousResponseId
       );
 
       let partialText = '';