diff --git a/examples/hf0-demo.ts b/examples/hf0-demo.ts
index ae9b46d..e66f10d 100644
--- a/examples/hf0-demo.ts
+++ b/examples/hf0-demo.ts
@@ -57,12 +57,14 @@ async function main() {
       messages: [
         {
           role: 'system',
-          content: `You are a McKinsey analyst who is an expert at writing executive summaries.`
+          content: `You are a McKinsey analyst who is an expert at writing executive summaries. Be srue to cite your sources using markdown.`
         },
         {
           role: 'user',
-          content: `Write a thorough executive summary on this topic: {{topic}}.
-          In order to do this, you will need to answer the following questions: \n{{#questions}}- {{.}}\n{{/questions}}`
+          content: (input) =>
+            `Write a thorough executive summary on this topic: ${topic}. In order to do this, you will need to answer the following questions: \n${input.questions
+              .map((q) => `- ${q}`)
+              .join('\n')}`
         }
       ],
       model: 'gpt-4-32k'
diff --git a/examples/search-and-crawl.ts b/examples/search-and-crawl.ts
index 4f0a071..fe8d527 100644
--- a/examples/search-and-crawl.ts
+++ b/examples/search-and-crawl.ts
@@ -30,7 +30,7 @@ async function main() {
         topic: z.string()
       })
     )
-    .callWithMetadata({ topic })
+    .call({ topic })
 
   console.log('\n\n\n')
   console.log(res)
diff --git a/examples/summarize-news.ts b/examples/summarize-news.ts
index 55ebe0d..0c5fcab 100644
--- a/examples/summarize-news.ts
+++ b/examples/summarize-news.ts
@@ -11,7 +11,7 @@ async function main() {
   const topic = process.argv[2] || 'HF0 accelerator'
 
   const res = await agentic
-    .gpt4(`Summarize the latest news on {{topic}} using markdown.`)
+    .gpt3(`Summarize the latest news on {{topic}} using markdown.`)
     .tools([new SerpAPITool()])
     .input(
       z.object({
diff --git a/src/agentic.ts b/src/agentic.ts
index 9b448fb..08165af 100644
--- a/src/agentic.ts
+++ b/src/agentic.ts
@@ -7,7 +7,7 @@ import { HumanFeedbackOptions, HumanFeedbackType } from './human-feedback'
 import { HumanFeedbackMechanismCLI } from './human-feedback/cli'
 import { OpenAIChatCompletion } from './llms/openai'
 import { defaultLogger } from './logger'
-import { defaultIDGeneratorFn } from './utils'
+import { defaultIDGeneratorFn, isFunction, isString } from './utils'
 
 export class Agentic {
   // _taskMap: WeakMap<string, BaseTask<any, any>>
@@ -103,16 +103,24 @@ export class Agentic {
     return this._idGeneratorFn
   }
 
-  openaiChatCompletion(
-    promptOrChatCompletionParams: string | types.openai.ChatCompletionParams, // TODO: make more strict?
+  openaiChatCompletion<TInput extends types.TaskInput = any>(
+    promptOrChatCompletionParams:
+      | types.ChatMessageContent<TInput>
+      | SetOptional<types.OpenAIChatCompletionParamsInput<TInput>, 'model'>,
     modelParams?: SetOptional<
-      types.openai.ChatCompletionParams,
+      types.OpenAIChatCompletionParamsInput,
       'model' | 'messages'
     >
   ) {
-    let options: Partial<types.openai.ChatCompletionParams>
+    let options: SetOptional<
+      types.OpenAIChatCompletionParamsInput<TInput>,
+      'model'
+    >
 
-    if (typeof promptOrChatCompletionParams === 'string') {
+    if (
+      isString(promptOrChatCompletionParams) ||
+      isFunction(promptOrChatCompletionParams)
+    ) {
       options = {
         ...modelParams,
         messages: [
@@ -130,9 +138,9 @@ export class Agentic {
       }
     }
 
-    return new OpenAIChatCompletion({
+    return new OpenAIChatCompletion<TInput>({
+      ...this._openaiModelDefaults,
       agentic: this,
-      ...(this._openaiModelDefaults as any), // TODO
       ...options
     })
   }
@@ -140,18 +148,24 @@ export class Agentic {
   /**
    * Shortcut for creating an OpenAI chat completion call with the `gpt-3.5-turbo` model.
    */
-  gpt3(
+  gpt3<TInput extends types.TaskInput = any>(
     promptOrChatCompletionParams:
-      | string
-      | SetOptional<types.openai.ChatCompletionParams, 'model'>,
+      | types.ChatMessageContent<TInput>
+      | SetOptional<types.OpenAIChatCompletionParamsInput<TInput>, 'model'>,
     modelParams?: SetOptional<
-      types.openai.ChatCompletionParams,
+      types.OpenAIChatCompletionParamsInput,
       'model' | 'messages'
     >
   ) {
-    let options: SetOptional<types.openai.ChatCompletionParams, 'model'>
+    let options: SetOptional<
+      types.OpenAIChatCompletionParamsInput<TInput>,
+      'model'
+    >
 
-    if (typeof promptOrChatCompletionParams === 'string') {
+    if (
+      isString(promptOrChatCompletionParams) ||
+      isFunction(promptOrChatCompletionParams)
+    ) {
       options = {
         ...modelParams,
         messages: [
@@ -169,9 +183,9 @@ export class Agentic {
       }
     }
 
-    return new OpenAIChatCompletion({
+    return new OpenAIChatCompletion<TInput>({
+      ...this._openaiModelDefaults,
       agentic: this,
-      ...(this._openaiModelDefaults as any), // TODO
       model: 'gpt-3.5-turbo',
       ...options
     })
@@ -180,18 +194,24 @@ export class Agentic {
   /**
    * Shortcut for creating an OpenAI chat completion call with the `gpt-4` model.
    */
-  gpt4(
+  gpt4<TInput extends types.TaskInput = any>(
     promptOrChatCompletionParams:
-      | string
-      | SetOptional<types.openai.ChatCompletionParams, 'model'>,
+      | types.ChatMessageContent<TInput>
+      | SetOptional<types.OpenAIChatCompletionParamsInput<TInput>, 'model'>,
     modelParams?: SetOptional<
-      types.openai.ChatCompletionParams,
+      types.OpenAIChatCompletionParamsInput,
       'model' | 'messages'
     >
   ) {
-    let options: SetOptional<types.openai.ChatCompletionParams, 'model'>
+    let options: SetOptional<
+      types.OpenAIChatCompletionParamsInput<TInput>,
+      'model'
+    >
 
-    if (typeof promptOrChatCompletionParams === 'string') {
+    if (
+      isString(promptOrChatCompletionParams) ||
+      isFunction(promptOrChatCompletionParams)
+    ) {
       options = {
         ...modelParams,
         messages: [
@@ -209,9 +229,9 @@ export class Agentic {
       }
     }
 
-    return new OpenAIChatCompletion({
+    return new OpenAIChatCompletion<TInput>({
+      ...this._openaiModelDefaults,
       agentic: this,
-      ...(this._openaiModelDefaults as any), // TODO
       model: 'gpt-4',
       ...options
     })
diff --git a/src/types.ts b/src/types.ts
index 07499f2..3f8ecd9 100644
--- a/src/types.ts
+++ b/src/types.ts
@@ -80,9 +80,17 @@ export type ChatMessageContent<TInput extends TaskInput = void> =
 export type ChatMessageInput<TInput extends TaskInput = void> =
   | ChatMessage
   | {
+      role: ChatMessageRole
+      name?: string
+      function_call?: any
       content: ChatMessageContent<TInput>
     }
 
+export type OpenAIChatCompletionParamsInput<TInput extends TaskInput = void> =
+  Omit<openai.ChatCompletionParams, 'messages'> & {
+    messages: ChatMessageInput<TInput>[]
+  }
+
 export interface ChatModelOptions<
   TInput extends TaskInput = void,
   TOutput extends TaskOutput = string,
diff --git a/test/utils.test.ts b/test/utils.test.ts
index d664000..641a56c 100644
--- a/test/utils.test.ts
+++ b/test/utils.test.ts
@@ -35,6 +35,8 @@ test('sleep should delay execution', async (t) => {
   const start = Date.now()
   await sleep(1000) // for example, 1000ms / 1sec
   const end = Date.now()
+
+  // NOTE (travis): I was seeing sporadic failures on CI here, so I added a 10ms buffer
   const duration = end - start
   t.true(duration >= 1000 - 10)
 })