ChatMistralAI integration

Integrate with the ChatMistralAI chat model using LangChain JavaScript.

Mistral AI is a platform that offers hosting for their powerful open source models.

This will help you getting started with Mistral chat models. For detailed documentation of all ChatMistralAI features and configurations head to the API reference.

Overview

Integration details

Class	Package	Serializable	PY support	Downloads	Version
ChatMistralAI	@langchain/mistralai	❌	✅

Model features

See the links in the table headers below for guides on how to use specific features.

Tool calling	Structured output	Image input	Audio input	Video input	Token-level streaming	Token usage	Logprobs
✅	✅	✅	❌	❌	✅	✅	❌

Setup

To access Mistral AI models you’ll need to create a Mistral AI account, get an API key, and install the @langchain/mistralai integration package.

Credentials

Visit the Mistral console to sign up and generate an API key. Once you’ve done this set the MISTRAL_API_KEY environment variable:

export MISTRAL_API_KEY="your-api-key"

If you want to get automated tracing of your model calls you can also set your LangSmith API key by uncommenting below:

# export LANGSMITH_TRACING="true"
# export LANGSMITH_API_KEY="your-api-key"

Installation

The LangChain ChatMistralAI integration lives in the @langchain/mistralai package:

npm

npm install @langchain/mistralai @langchain/core

yarn add @langchain/mistralai @langchain/core

pnpm add @langchain/mistralai @langchain/core

Instantiation

Now we can instantiate our model object and generate chat completions:

import { ChatMistralAI } from "@langchain/mistralai"

const llm = new ChatMistralAI({
    model: "mistral-large-latest",
    temperature: 0,
    maxRetries: 2,
    // other params...
})

Invocation

When sending chat messages to mistral, there are a few requirements to follow:

• The first message can not be an assistant (ai) message.
• Messages must alternate between user and assistant (ai) messages.
• Messages can not end with an assistant (ai) or system message.

const aiMsg = await llm.invoke([
    [
        "system",
        "You are a helpful assistant that translates English to French. Translate the user sentence.",
    ],
    ["human", "I love programming."],
])
aiMsg

AIMessage {
  "content": "J'adore la programmation.",
  "additional_kwargs": {},
  "response_metadata": {
    "tokenUsage": {
      "completionTokens": 9,
      "promptTokens": 27,
      "totalTokens": 36
    },
    "finish_reason": "stop"
  },
  "tool_calls": [],
  "invalid_tool_calls": [],
  "usage_metadata": {
    "input_tokens": 27,
    "output_tokens": 9,
    "total_tokens": 36
  }
}

console.log(aiMsg.content)

J'adore la programmation.

Tool calling

Mistral’s API supports tool calling for a subset of their models. You can see which models support tool calling on this page.

The examples below demonstrates how to use it:

import { ChatMistralAI } from "@langchain/mistralai";
import { ChatPromptTemplate } from "@langchain/core/prompts";
import * as z from "zod";
import { tool } from "@langchain/core/tools";

const calculatorSchema = z.object({
  operation: z
    .enum(["add", "subtract", "multiply", "divide"])
    .describe("The type of operation to execute."),
  number1: z.number().describe("The first number to operate on."),
  number2: z.number().describe("The second number to operate on."),
});

const calculatorTool = tool((input) => {
  return JSON.stringify(input);
}, {
  name: "calculator",
  description: "A simple calculator tool",
  schema: calculatorSchema,
});

// Bind the tool to the model
const modelWithTool = new ChatMistralAI({
  model: "mistral-large-latest",
}).bindTools([calculatorTool]);


const calcToolPrompt = ChatPromptTemplate.fromMessages([
  [
    "system",
    "You are a helpful assistant who always needs to use a calculator.",
  ],
  ["human", "{input}"],
]);

// Chain your prompt, model, and output parser together
const chainWithCalcTool = calcToolPrompt.pipe(modelWithTool);

const calcToolRes = await chainWithCalcTool.invoke({
  input: "What is 2 + 2?",
});
console.log(calcToolRes.tool_calls);

[
  {
    name: 'calculator',
    args: { operation: 'add', number1: 2, number2: 2 },
    type: 'tool_call',
    id: 'DD9diCL1W'
  }
]

Hooks

Mistral AI supports custom hooks for three events: beforeRequest, requestError, and response. Examples of the function signature for each hook type can be seen below:

const beforeRequestHook = (req: Request): Request | void | Promise<Request | void> => {
    // Code to run before a request is processed by Mistral
};

const requestErrorHook = (err: unknown, req: Request): void | Promise<void> => {
    // Code to run when an error occurs as Mistral is processing a request
};

const responseHook = (res: Response, req: Request): void | Promise<void> => {
    // Code to run before Mistral sends a successful response
};

To add these hooks to the chat model, either pass them as arguments and they are automatically added:

import { ChatMistralAI } from "@langchain/mistralai"

const modelWithHooks = new ChatMistralAI({
    model: "mistral-large-latest",
    temperature: 0,
    maxRetries: 2,
    beforeRequestHooks: [ beforeRequestHook ],
    requestErrorHooks: [ requestErrorHook ],
    responseHooks: [ responseHook ],
    // other params...
});

Or assign and add them manually after instantiation:

import { ChatMistralAI } from "@langchain/mistralai"

const model = new ChatMistralAI({
    model: "mistral-large-latest",
    temperature: 0,
    maxRetries: 2,
    // other params...
});

model.beforeRequestHooks = [ ...model.beforeRequestHooks, beforeRequestHook ];
model.requestErrorHooks = [ ...model.requestErrorHooks, requestErrorHook ];
model.responseHooks = [ ...model.responseHooks, responseHook ];

model.addAllHooksToHttpClient();

The method addAllHooksToHttpClient clears all currently added hooks before assigning the entire updated hook lists to avoid hook duplication.

Hooks can be removed one at a time, or all hooks can be cleared from the model at once.

model.removeHookFromHttpClient(beforeRequestHook);

model.removeAllHooksFromHttpClient();

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API reference

For detailed documentation of all ChatMistralAI features and configurations head to the API reference.

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