diff --git a/bin/chat.js b/bin/chat.js
index f4be69c3..181c9a31 100644
--- a/bin/chat.js
+++ b/bin/chat.js
@@ -1,16 +1,19 @@
 import { tools } from './tools.js'
 
-const systemPrompt = 'You are a machine learning web application named "Hyperparam".'
-  + ' You assist users with building high quality ML models by introspecting on their training set data.'
+/** @type {'text' | 'tool'} */
+let outputMode = 'text' // default output mode
+
+function systemPrompt() {
+  return 'You are a machine learning web application named "Hyperparam" running on a CLI terminal.'
+  + '\nYou assist users with analyzing and exploring datasets, particularly in parquet format.'
   + ' The website and api are available at hyperparam.app.'
-  + ' Hyperparam uses LLMs to analyze their own training set.'
-  + ' It can generate the perplexity, entropy, and other metrics of the training set.'
-  + ' This allows users to find segments of their data set which are difficult to model.'
-  + ' This could be because the data is junk, or because the data requires deeper understanding.'
-  + ' This is essential for closing the loop on the ML lifecycle.'
-  + ' The quickest way to get started is to upload a dataset and start exploring.'
+  + ' The Hyperparam CLI tool can list and explore local parquet files.'
+  + '\nYou are on a terminal and can only output: text, emojis, terminal colors, and terminal formatting.'
+  + ' Don\'t add additional markdown or html formatting unless requested.'
+  + (process.stdout.isTTY ? ` The terminal width is ${process.stdout.columns} characters.` : '')
+}
 /** @type {Message} */
-const systemMessage = { role: 'system', content: systemPrompt }
+const systemMessage = { role: 'system', content: systemPrompt() }
 
 const colors = {
   system: '\x1b[36m', // cyan
@@ -43,6 +46,7 @@ async function sendToServer(chatInput) {
   if (!reader) throw new Error('No response body')
   const decoder = new TextDecoder()
   let buffer = ''
+  const write = writeWithColor()
 
   while (true) {
     const { done, value } = await reader.read()
@@ -57,6 +61,11 @@ async function sendToServer(chatInput) {
         const chunk = JSON.parse(line)
         const { type, error } = chunk
         if (type === 'response.output_text.delta') {
+          // text mode
+          if (outputMode === 'tool') {
+            write('\n')
+          }
+          outputMode = 'text'
           streamResponse.content += chunk.delta
           write(chunk.delta)
         } else if (error) {
@@ -93,7 +102,7 @@ async function sendMessages(messages) {
   const response = await sendToServer(chatInput)
   messages.push(response)
   // handle tool results
-  if (response.tool_calls) {
+  if (response.tool_calls?.length) {
     /** @type {{ toolCall: ToolCall, tool: ToolHandler, result: Promise<string> }[]} */
     const toolResults = []
     for (const toolCall of response.tool_calls) {
@@ -106,7 +115,11 @@ async function sendMessages(messages) {
         throw new Error(`Unknown tool: ${toolCall.function.name}`)
       }
     }
-    write('\n')
+    // tool mode
+    if (outputMode === 'text') {
+      write('\n')
+    }
+    outputMode = 'tool' // switch to tool output mode
     for (const toolResult of toolResults) {
       const { toolCall, tool } = toolResult
       try {
@@ -123,14 +136,14 @@ async function sendMessages(messages) {
           const pairs = entries.map(([key, value]) => `${key} = ${value}`)
           func += `(${pairs.join(', ')})`
         }
-
-        write(colors.tool, `${tool.emoji} ${func}`, colors.normal, '\n\n')
+        write(colors.tool, `${tool.emoji} ${func}`, colors.normal, '\n')
         messages.push({ role: 'tool', content, tool_call_id: toolCall.id })
       } catch (error) {
-        write(colors.error, `\nError calling tool ${toolCall.function.name}: ${error.message}\n\n`, colors.normal)
+        write(colors.error, `\nError calling tool ${toolCall.function.name}: ${error.message}`, colors.normal)
         messages.push({ role: 'tool', content: `Error calling tool ${toolCall.function.name}: ${error.message}`, tool_call_id: toolCall.id })
       }
     }
+
     // send messages with tool results
     await sendMessages(messages)
   }
@@ -143,6 +156,45 @@ function write(...args) {
   args.forEach(s => process.stdout.write(s))
 }
 
+/**
+ * Handle streaming output, but buffer if needed to handle escape codes.
+ * @returns {(...args: string[]) => void}
+ */
+function writeWithColor() {
+  /** @type {string | undefined} */
+  let buffer
+  /**
+   * @param {string} char
+   */
+  function writeChar(char) {
+    if (buffer === undefined && char !== '\\' && char !== '\x1b') {
+      write(char)
+    } else {
+      buffer ??= ''
+      buffer += char
+      const isEscape = buffer.startsWith('\\x1b[') || buffer.startsWith('\\033[')
+      // if the buffer is an escape sequence, write it
+      if (isEscape) {
+        // convert to terminal escape sequence
+        const escaped = buffer.replace(/\\x1b\[/g, '\x1b[').replace(/\\033\[/g, '\x1b[')
+        write(escaped)
+        buffer = undefined
+      } else if (buffer.length > 6) {
+        // no match, just write it
+        write(buffer)
+        buffer = undefined
+      }
+    }
+  }
+  return (...args) => {
+    for (const arg of args) {
+      for (const char of arg) {
+        writeChar(char)
+      }
+    }
+  }
+}
+
 export function chat() {
   /** @type {Message[]} */
   const messages = [systemMessage]
@@ -157,6 +209,7 @@ export function chat() {
     } else if (input) {
       try {
         write(colors.user, 'answer: ', colors.normal)
+        outputMode = 'text' // switch to text output mode
         messages.push({ role: 'user', content: input.trim() })
         await sendMessages(messages)
       } catch (error) {