第 0 关
你的工具箱
EventBus
四个零件
-
模型
model角色
读文本,写文本。它从训练中学到了很多,但对你的应用、你的用户和今天发生的事一无所知。
-
system prompt
system装备
放在每次请求最前面的指令:它是谁、它的规则、它的语气,以及它自己无从得知的事实。
-
消息
messages[]背包
到目前为止的对话。你的代码保存这个列表,并在每次调用时完整发送。
-
工具
tools技能
描述模型可以申请调用的函数的卡片。它只能申请:真正执行的是你的代码。
模型什么都不记得
这一点最让人意外。模型在两次调用之间没有任何记忆。每次请求都从零开始,它只知道这次请求里装着的东西:system prompt、消息和工具列表。
在动画里,第二个问题单独到达,神谕者问“哪个城市?”,尽管刚刚才有人告诉过它。只有当你的代码把之前的消息重新发过去,它才“记得”。聊天应用看起来有记忆,是因为它们每次都把整段对话重新发送一遍。
由此可以得出两点。历史记录归你管:由你来保存、裁剪和存储。而你保留的每条消息,每次调用都会再发送一次,所以对话越长,每次的成本就越高。
文本,还是一个请求
当它的列表里有工具时,回复可以是两种之一:给用户的文本,或者用某些输入调用某个工具的请求。模型从不执行任何东西。它写下
get_forecast(city, date) 就停下了;执行它是你的代码的工作。
注意那个日期:模型把“明天”换算成了 2026-09-26,因为 system prompt 告诉了它今天是几号。它自己无从得知的事实,就该放在那里。
代码
使用 astorlm:一个 astorlm 智能体拥有同样的四个零件。它会在多次 run()
调用之间替你保存历史记录;当模型申请调用工具时,它会执行工具并把结果送回去。这个循环就是第 2 关。
从零手写:四个零件加一次请求,还没有循环。把 LLM 配置块换成你自己的端点、模型和密钥。
import { OpenAIProvider, createLocalAgent, tool } from 'astorlm'
import { z } from 'zod'
// A tool: the card the model reads (name, description, schema) plus your code behind it.
const getForecast = tool({
name: 'get_forecast',
description: 'Daily forecast for one city: rain chance and min/max temp. date is YYYY-MM-DD.',
schema: z.object({ city: z.string(), date: z.string() }),
execute: async ({ city, date }) => forecastLine(city, date), // your code; the model never sees it
})
const agent = await createLocalAgent({
// Any OpenAI-compatible endpoint: OpenAI, Ollama, LM Studio, vLLM, a proxy…
provider: new OpenAIProvider({
baseURL: 'http://localhost:11434/v1', // e.g. Ollama's default address
model: 'your-model', // e.g. 'llama3.1', 'gpt-4o-mini'
apiKey: 'YOUR_API_KEY', // local servers usually ignore it
}),
systemPrompt: 'You are Nimbus, a weather assistant. Today is 2026-09-25. Answer in one short line.',
contextFiles: [], // by default astorlm also appends AGENTS.md and CLAUDE.md from the working folder
tools: [getForecast],
})
// The agent keeps the history for you, so the second run knows about the first.
await agent.run('I’m in Buenos Aires.')
await agent.run('Will it rain tomorrow?') // asks for get_forecast(Buenos Aires, 2026-09-26), runs it, answers
console.log(agent.getMessages().length) // every message so far, resent on every call
// The four pieces, with no agent yet: one request in, one reply out. Plain fetch, no SDK.
// Any OpenAI-compatible endpoint: OpenAI, Ollama, LM Studio, vLLM, a proxy…
const LLM = {
baseURL: 'http://localhost:11434/v1', // e.g. Ollama's default address
model: 'your-model', // e.g. 'llama3.1', 'gpt-4o-mini'
apiKey: 'YOUR_API_KEY', // local servers usually ignore it
}
type ToolCall = { id: string; function: { name: string; arguments: string } }
type Message =
| { role: 'user'; content: string }
| { role: 'assistant'; content: string | null; tool_calls?: ToolCall[] }
// 1. The system prompt: who it is, its rules, and facts it can't know on its own.
const system = 'You are Nimbus, a weather assistant. Today is 2026-09-25. Answer in one short line.'
// 2. The history. The model remembers nothing between calls: this array IS its memory.
const messages: Message[] = []
// 3. A tool, as the model sees it: a name, a description and its inputs. Never the code.
const tools = [
{
type: 'function',
function: {
name: 'get_forecast',
description: 'Daily forecast for one city: rain chance and min/max temp. date is YYYY-MM-DD.',
parameters: {
type: 'object',
properties: { city: { type: 'string' }, date: { type: 'string' } },
required: ['city', 'date'],
},
},
},
]
// 4. The model: every call sends ALL of the above, and gets back one message.
async function ask(text: string): Promise<Message> {
messages.push({ role: 'user', content: text })
const res = await fetch(`${LLM.baseURL}/chat/completions`, {
method: 'POST',
headers: { 'content-type': 'application/json', authorization: `Bearer ${LLM.apiKey}` },
body: JSON.stringify({ model: LLM.model, messages: [{ role: 'system', content: system }, ...messages], tools }),
})
const reply: Message = (await res.json()).choices[0].message
messages.push(reply) // keep it, or the next call won't know it happened
return reply
}
await ask('I’m in Buenos Aires.') // "Got it! How can I help?"
const reply = await ask('Will it rain tomorrow?')
// The reply is either text (reply.content) or a tool request (reply.tool_calls):
// get_forecast({ city: "Buenos Aires", date: "2026-09-26" })
// Running it and sending the result back, in a loop, is level 2.
# The four pieces, with no agent yet: one request in, one reply out. Standard library only, no SDK.
import json
import urllib.request
# Any OpenAI-compatible endpoint: OpenAI, Ollama, LM Studio, vLLM, a proxy...
LLM = {
"base_url": "http://localhost:11434/v1", # e.g. Ollama's default address
"model": "your-model", # e.g. "llama3.1", "gpt-4o-mini"
"api_key": "YOUR_API_KEY", # local servers usually ignore it
}
# 1. The system prompt: who it is, its rules, and facts it can't know on its own.
SYSTEM = "You are Nimbus, a weather assistant. Today is 2026-09-25. Answer in one short line."
# 2. The history. The model remembers nothing between calls: this list IS its memory.
messages = []
# 3. A tool, as the model sees it: a name, a description and its inputs. Never the code.
TOOLS = [
{
"type": "function",
"function": {
"name": "get_forecast",
"description": "Daily forecast for one city: rain chance and min/max temp. date is YYYY-MM-DD.",
"parameters": {
"type": "object",
"properties": {"city": {"type": "string"}, "date": {"type": "string"}},
"required": ["city", "date"],
},
},
}
]
# 4. The model: every call sends ALL of the above, and gets back one message.
def ask(text):
messages.append({"role": "user", "content": text})
request = urllib.request.Request(
f"{LLM['base_url']}/chat/completions",
data=json.dumps({
"model": LLM["model"],
"messages": [{"role": "system", "content": SYSTEM}, *messages],
"tools": TOOLS,
}).encode(),
headers={"Content-Type": "application/json", "Authorization": f"Bearer {LLM['api_key']}"},
)
with urllib.request.urlopen(request) as response:
reply = json.load(response)["choices"][0]["message"]
messages.append(reply) # keep it, or the next call won't know it happened
return reply
ask("I'm in Buenos Aires.") # "Got it! How can I help?"
reply = ask("Will it rain tomorrow?")
# The reply is either text (reply["content"]) or a tool request (reply["tool_calls"]):
# get_forecast(city="Buenos Aires", date="2026-09-26")
# Running it and sending the result back, in a loop, is level 2.
注意事项
- 让 system prompt 简短而具体。每次调用它都会跟着发送。写清角色、规则、语气和模型需要的事实,不要写成一本手册。
- 决定历史记录保留什么。永远把一切都重新发送,会变慢、变贵,最后还会装不下。裁剪和总结历史记录本身就是一个模式。
- 没有工具的模型照样会回答。问它实时数据,它会流畅地瞎猜。如果答案取决于它看不到的东西,就给它一个工具。