Agent Engineering
5 Messages Behind One Conversation
Left: what the user sees | Right: what actually happens in the API. Scroll down to auto-play what happens behind a single weather query.
7 steps · Watch what happens behind a single weather query
JSON Format Reference
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Complete format of the messages array
{
"messages": [
{
"role": "system",
"content": "instruction"
},
{
"role": "user",
"content": "user message"
},
{
"role": "assistant",
"content": null,
"tool_calls": [{
"name": "…",
"arguments": {…}
}]
},
{
"role": "tool",
"tool_call_id": "…",
"content": "result"
},
{
"role": "assistant",
"content": "final response"
}
]
}
// 5 messages total
// 2 model API calls
// 1 tool call
Takeaway
Takeaway The user sees one response. Behind it: 5 messages, 2 model API calls, 1 external API call. The essence of product design is deciding which of these steps the user perceives — and which are handled silently.