How to integrate Sevdesk MCP with Vercel AI SDK v6

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Introduction

This guide walks you through connecting Sevdesk to Vercel AI SDK v6 using the Composio tool router. By the end, you'll have a working Sevdesk agent that can generate and send a new invoice, list all unpaid customer invoices, add a new business expense entry through natural language commands.

This guide will help you understand how to give your Vercel AI SDK agent real control over a Sevdesk account through Composio's Sevdesk MCP server.

Before we dive in, let's take a quick look at the key ideas and tools involved.

Also integrate Sevdesk with

TL;DR

Here's what you'll learn:
  • How to set up and configure a Vercel AI SDK agent with Sevdesk integration
  • Using Composio's Tool Router to dynamically load and access Sevdesk tools
  • Creating an MCP client connection using HTTP transport
  • Building an interactive CLI chat interface with conversation history management
  • Handling tool calls and results within the Vercel AI SDK framework

What is Vercel AI SDK?

The Vercel AI SDK is a TypeScript library for building AI-powered applications. It provides tools for creating agents that can use external services and maintain conversation state.

Key features include:

  • streamText: Core function for streaming responses with real-time tool support
  • MCP Client: Built-in support for Model Context Protocol via @ai-sdk/mcp
  • Step Counting: Control multi-step tool execution with stopWhen: stepCountIs()
  • OpenAI Provider: Native integration with OpenAI models

What is the Sevdesk MCP server, and what's possible with it?

The Sevdesk MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Sevdesk account. It provides structured and secure access to your accounting workspace, so your agent can perform actions like managing invoices, tracking expenses, generating reports, organizing contacts, and handling payments on your behalf.

  • Invoice creation and management: Instantly generate, send, and track invoices for your clients, keeping your business cash flow streamlined.
  • Expense tracking and categorization: Let your agent record and organize expenses, ensuring your books are always up to date and categorized for tax time.
  • Financial reporting and insights: Request detailed reports and summaries—like profit and loss or balance sheets—so you can make informed business decisions quickly.
  • Contact and customer management: Effortlessly add, update, or retrieve customer details and supplier information to keep your records accurate.
  • Payment and transaction handling: Enable your agent to log payments, match transactions, and help reconcile your accounts, reducing manual entry and errors.

Supported Tools & Triggers

Tools
Book Invoice AmountTool to book an invoice amount in SevDesk.
Check Customer Number AvailabilityTool to check if a customer number is available in sevDesk.
Create Accounting ContactTool to create a new accounting contact in sevDesk.
Create Check Account TransactionTool to create a new check account transaction in SevDesk.
Create Clearing AccountTool to create a new clearing account in sevDesk.
Create Communication WayTool to create a new contact communication way (email, phone, website, etc.
Create ContactCreates a new contact (person or company) in SevDesk accounting system.
Create Contact (REST API)Tool to create a new contact in sevDesk using the standard REST API endpoint.
Create Contact AddressTool to create a new contact address in SevDesk.
Create Contact Custom FieldTool to create a custom field for a contact in sevDesk.
Create Contact Custom Field SettingCreates a new contact custom field setting in sevDesk for tracking additional contact information.
Create Credit Note from InvoiceTool to create a new credit note from an existing invoice in SevDesk.
Create File Import AccountTool to create a new file import account (check account) in sevDesk.
Create PartTool to create a new part (product or service) in SevDesk.
Create Payment MethodCreates a new payment method in sevDesk for tracking different payment types.
Create Private Transaction RuleTool to create a new private transaction rule in SevDesk.
Create TagTool to create a new tag and attach it to an object (Invoice, Order, Voucher, or CreditNote) in sevDesk.
Delete Accounting Contact By IDPermanently deletes an accounting contact from sevDesk by its unique identifier.
Delete Check Account By IDPermanently deletes a check account from sevDesk by its unique identifier.
Delete Check Account TransactionPermanently deletes a check account transaction from sevDesk by its unique identifier.
Delete Communication Way By IDPermanently deletes a communication way from sevDesk by its unique identifier.
Delete ContactPermanently deletes a contact from sevDesk by its unique identifier.
Delete Contact Address By IDTool to delete a contact address from sevDesk by its unique identifier.
Delete Contact Custom Field By IDTool to permanently delete a contact custom field by its ID.
Delete Contact Custom Field Setting By IDTool to permanently delete a contact custom field setting by its ID.
Delete Credit Note By IDPermanently deletes a credit note from sevDesk by its unique identifier.
Delete Order By IDPermanently deletes an order from sevDesk by its unique identifier.
Delete Order Position By IDPermanently deletes an order position from sevDesk by its unique identifier.
Delete Payment MethodDeletes a payment method in sevDesk by its ID.
Delete Private Transaction Rule By IDPermanently deletes a private transaction rule from sevDesk by its unique identifier.
Delete Tag By IDPermanently deletes a tag from sevDesk by its unique identifier.
Enshrine Check Account TransactionTool to enshrine a check account transaction by its ID.
Export Credit Note CSVTool to export credit notes as CSV from SevDesk.
Fetch Dictionary Entries By TypeTool to retrieve placeholders (dictionary entries) for a specific object type in sevDesk.
Find Contacts By Custom Field ValueTool to find contacts by custom field value.
Generate Progress Download HashTool to generate a download hash for an export job progress.
Get Accounting Contact By IDTool to retrieve accounting contact details by ID.
Get Accounting ContactsTool to retrieve accounting contacts from sevDesk.
Get SevClient Account InvoicesRetrieves all sevDesk account invoices for the authenticated client.
Get Check Account Balance At DateTool to get the balance of a check account at a specific date.
Get Check Account By IDTool to retrieve details of a specific check account by ID.
Get Check AccountsTool to retrieve a list of all check accounts.
Get Check Account Transaction By IDTool to retrieve a specific check account transaction by its ID.
Get Check Account TransactionsTool to retrieve list of check account transactions.
Get CommunicationWay By IDTool to retrieve details of a specific communication way by ID.
Get Communication Way KeysRetrieve a list of communication way keys from sevDesk.
Get Communication WaysTool to retrieve communication ways from sevDesk.
Get Contact Address By IDTool to retrieve details of a specific contact address by ID.
Get Contact AddressesTool to retrieve contact addresses from sevdesk.
Get Contact By IDTool to retrieve details of a specific contact by ID.
Get Contact Custom Field By IDTool to retrieve a contact custom field by its ID.
Get Contact Custom FieldsTool to retrieve contact custom fields from sevDesk.
Get Contact Custom Field Setting By IDTool to retrieve details of a specific contact custom field setting by ID.
Get Contact Custom Field Setting Reference CountTool to receive the count of references for a contact custom field setting.
Get Contact Custom Field SettingsTool to retrieve contact custom field settings from sevDesk.
Get ContactsTool to retrieve a list of contacts.
Get Contact Tabs Item CountTool to get the count of items across all tabs for a specific contact.
Get Credit Note PositionsTool to retrieve credit note positions from SevDesk.
Get Credit NotesTool to retrieve a list of credit notes.
Get Export Invoice CSVTool to export invoices as CSV from sevDesk.
Get Export Transactions CSVTool to export check account transactions as CSV file.
Get Invoice Is Partially PaidTool to check if an invoice is already partially paid.
Get Invoice PositionsTool to retrieve all line items (positions) for a specific invoice.
Get Invoice PositionsTool to retrieve invoice positions from sevDesk.
Get InvoicesRetrieves a list of invoices from sevDesk with optional filtering and pagination.
Get Letterpapers With ThumbnailsTool to retrieve all available letterpapers with thumbnails from sevDesk.
Get Next Customer NumberTool to retrieve the next free customer number from sevDesk.
Get Order By IDTool to retrieve details of a specific order by ID.
Get Order DiscountsTool to retrieve discounts applied to a specific order in sevDesk.
Get Order Position By IDTool to retrieve details of a specific order position by ID.
Get Order PositionsTool to retrieve order positions from SevDesk.
Get OrdersRetrieve a paginated list of orders from sevDesk.
Get Part By IDTool to retrieve details of a specific part by ID.
Get Part Contact PricesTool to retrieve a list of part contact prices.
Get PartsTool to retrieve a list of all parts.
Get Part StockTool to retrieve the current stock level of a specific part.
Get Part UnitiesRetrieves a list of part unities (units of measurement) from SevDesk.
Get Payment MethodsRetrieves all available payment methods from sevDesk.
Get PlacesRetrieve a list of places (cities/locations with geographic data) from sevDesk.
Get Private Transaction RulesTool to list existing private transaction rules in SevDesk.
Get Export ProgressTool to retrieve the progress of an export operation.
Get Receipt Guidance For Account NumberTool to retrieve receipt guidance for a specific Datev account number.
Get Receipt Guidance For All AccountsTool to retrieve receipt guidance for all accounts.
Get Receipt Guidance For ExpenseTool to retrieve guidance for expense accounts from sevDesk.
Get Receipt Guidance For RevenueTool to retrieve guidance for revenue accounts from sevDesk.
Get Receipt Guidance For Tax RuleTool to get guidance by tax rule from sevDesk.
Get Report Invoice ListTool to export invoice list report from sevDesk.
Get Report OrderlistTool to export the order list report from sevDesk.
Get SevClient ConfigRetrieves the sevClient configuration settings from sevDesk.
Get Tag By IDTool to retrieve details of a specific tag by ID.
Get Tag RelationsTool to retrieve tag relations from sevDesk.
Get TagsTool to retrieve tags from sevdesk.
Get Tax RulesRetrieves tax rules from SevDesk.
Get Bookkeeping System VersionTool to retrieve the bookkeeping system version from sevDesk.
Render InvoiceTool to render the PDF document of an invoice by its ID.
Reset Credit Note To OpenTool to reset a credit note status to open.
Save InvoiceTool to create a new invoice in SevDesk using the Factory endpoint.
Send Credit Note ByTool to mark a credit note as sent by updating its send status and type.
Send Credit Note By PrintingTool to send a credit note by printing and render it.
Send Invoice ByTool to mark an invoice as sent by specifying how it was sent to the customer.
Mark Order as SentTool to mark an order as sent in sevDesk.
Update Accounting ContactTool to update an existing accounting contact in SevDesk.
Update Check AccountUpdates an existing check account (bank account) in sevDesk by ID.
Update Check Account Transaction By IDTool to update an existing check account transaction in sevDesk.
Update Communication Way By IDTool to update an existing communication way by ID in sevDesk.
Update ContactTool to update an existing contact's details.
Update Contact Address By IDTool to update an existing contact address by its unique identifier.
Update Contact Custom FieldTool to update a contact custom field in SevDesk.
Update Contact Custom Field SettingTool to update an existing contact custom field setting in SevDesk.
Update Invoice ParameterTool to update an invoice parameter such as template, language, letterpaper, or PayPal settings.
Update Order By IDTool to update an existing order in sevDesk by ID.
Update Order TemplateTool to update an order parameter such as template, language, letterpaper, or PayPal settings.
Update Part By IDTool to update an existing part (product/service) in sevDesk.
Update SevClient Export ConfigTool to update the export configuration for a SevClient in sevDesk.
Update Tag By IDTool to update a tag's name in sevDesk by its ID.

What is the Composio tool router, and how does it fit here?

What is Composio SDK?

Composio's Composio SDK helps agents find the right tools for a task at runtime. You can plug in multiple toolkits (like Gmail, HubSpot, and GitHub), and the agent will identify the relevant app and action to complete multi-step workflows. This can reduce token usage and improve the reliability of tool calls. Read more here: Getting started with Composio SDK

The tool router generates a secure MCP URL that your agents can access to perform actions.

How the Composio SDK works

The Composio SDK follows a three-phase workflow:

  1. Discovery: Searches for tools matching your task and returns relevant toolkits with their details.
  2. Authentication: Checks for active connections. If missing, creates an auth config and returns a connection URL via Auth Link.
  3. Execution: Executes the action using the authenticated connection.

Step-by-step Guide

Prerequisites

Before you begin, make sure you have:
  • Node.js and npm installed
  • A Composio account with API key
  • An OpenAI API key

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key. You'll need credits to use the models, or you can connect to another model provider.
  • Keep the API key safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Navigate to your API settings and generate a new API key.
  • Store this key securely as you'll need it for authentication.

Install required dependencies

bash
npm install @ai-sdk/openai @ai-sdk/mcp @composio/core ai dotenv

First, install the necessary packages for your project.

What you're installing:

  • @ai-sdk/openai: Vercel AI SDK's OpenAI provider
  • @ai-sdk/mcp: MCP client for Vercel AI SDK
  • @composio/core: Composio SDK for tool integration
  • ai: Core Vercel AI SDK
  • dotenv: Environment variable management

Set up environment variables

bash
OPENAI_API_KEY=your_openai_api_key_here
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here

Create a .env file in your project root.

What's needed:

  • OPENAI_API_KEY: Your OpenAI API key for GPT model access
  • COMPOSIO_API_KEY: Your Composio API key for tool access
  • COMPOSIO_USER_ID: A unique identifier for the user session

Import required modules and validate environment

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Composio } from "@composio/core";
import * as readline from "readline";
import { streamText, type ModelMessage, stepCountIs } from "ai";
import { createMCPClient } from "@ai-sdk/mcp";

const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!process.env.OPENAI_API_KEY) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey,
});
What's happening:
  • We're importing all necessary libraries including Vercel AI SDK's OpenAI provider and Composio
  • The dotenv/config import automatically loads environment variables
  • The MCP client import enables connection to Composio's tool server

Create Tool Router session and initialize MCP client

typescript
async function main() {
  // Create a tool router session for the user
  const session = await composio.create(composioUserID!, {
    toolkits: ["sevdesk"],
  });

  const mcpUrl = session.mcp.url;
What's happening:
  • We're creating a Tool Router session that gives your agent access to Sevdesk tools
  • The create method takes the user ID and specifies which toolkits should be available
  • The returned mcp object contains the URL and authentication headers needed to connect to the MCP server
  • This session provides access to all Sevdesk-related tools through the MCP protocol

Connect to MCP server and retrieve tools

typescript
const mcpClient = await createMCPClient({
  transport: {
    type: "http",
    url: mcpUrl,
    headers: session.mcp.headers, // Authentication headers for the Composio MCP server
  },
});

const tools = await mcpClient.tools();
What's happening:
  • We're creating an MCP client that connects to our Composio Tool Router session via HTTP
  • The mcp.url provides the endpoint, and mcp.headers contains authentication credentials
  • The type: "http" is important - Composio requires HTTP transport
  • tools() retrieves all available Sevdesk tools that the agent can use

Initialize conversation and CLI interface

typescript
let messages: ModelMessage[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
console.log(
  "Ask any questions related to sevdesk, like summarize my last 5 emails, send an email, etc... :)))\n",
);

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  prompt: "> ",
});

rl.prompt();
What's happening:
  • We initialize an empty messages array to maintain conversation history
  • A readline interface is created to accept user input from the command line
  • Instructions are displayed to guide the user on how to interact with the agent

Handle user input and stream responses with real-time tool feedback

typescript
rl.on("line", async (userInput: string) => {
  const trimmedInput = userInput.trim();

  if (["exit", "quit", "bye"].includes(trimmedInput.toLowerCase())) {
    console.log("\nGoodbye!");
    rl.close();
    process.exit(0);
  }

  if (!trimmedInput) {
    rl.prompt();
    return;
  }

  messages.push({ role: "user", content: trimmedInput });
  console.log("\nAgent is thinking...\n");

  try {
    const stream = streamText({
      model: openai("gpt-5"),
      messages,
      tools,
      toolChoice: "auto",
      stopWhen: stepCountIs(10),
      onStepFinish: (step) => {
        for (const toolCall of step.toolCalls) {
          console.log(`[Using tool: ${toolCall.toolName}]`);
          }
          if (step.toolCalls.length > 0) {
            console.log(""); // Add space after tool calls
          }
        },
      });

      for await (const chunk of stream.textStream) {
        process.stdout.write(chunk);
      }

      console.log("\n\n---\n");

      // Get final result for message history
      const response = await stream.response;
      if (response?.messages?.length) {
        messages.push(...response.messages);
      }
    } catch (error) {
      console.error("\nAn error occurred while talking to the agent:");
      console.error(error);
      console.log(
        "\nYou can try again or restart the app if it keeps happening.\n",
      );
    } finally {
      rl.prompt();
    }
  });

  rl.on("close", async () => {
    await mcpClient.close();
    console.log("\n👋 Session ended.");
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});
What's happening:
  • We use streamText instead of generateText to stream responses in real-time
  • toolChoice: "auto" allows the model to decide when to use Sevdesk tools
  • stopWhen: stepCountIs(10) allows up to 10 steps for complex multi-tool operations
  • onStepFinish callback displays which tools are being used in real-time
  • We iterate through the text stream to create a typewriter effect as the agent responds
  • The complete response is added to conversation history to maintain context
  • Errors are caught and displayed with helpful retry suggestions

Complete Code

Here's the complete code to get you started with Sevdesk and Vercel AI SDK:

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Composio } from "@composio/core";
import * as readline from "readline";
import { streamText, type ModelMessage, stepCountIs } from "ai";
import { createMCPClient } from "@ai-sdk/mcp";

const composioAPIKey = process.env.COMPOSIO_API_KEY;
const composioUserID = process.env.COMPOSIO_USER_ID;

if (!process.env.OPENAI_API_KEY) throw new Error("OPENAI_API_KEY is not set");
if (!composioAPIKey) throw new Error("COMPOSIO_API_KEY is not set");
if (!composioUserID) throw new Error("COMPOSIO_USER_ID is not set");

const composio = new Composio({
  apiKey: composioAPIKey,
});

async function main() {
  // Create a tool router session for the user
  const session = await composio.create(composioUserID!, {
    toolkits: ["sevdesk"],
  });

  const mcpUrl = session.mcp.url;

  const mcpClient = await createMCPClient({
    transport: {
      type: "http",
      url: mcpUrl,
      headers: session.mcp.headers, // Authentication headers for the Composio MCP server
    },
  });

  const tools = await mcpClient.tools();

  let messages: ModelMessage[] = [];

  console.log("Chat started! Type 'exit' or 'quit' to end the conversation.\n");
  console.log(
    "Ask any questions related to sevdesk, like summarize my last 5 emails, send an email, etc... :)))\n",
  );

  const rl = readline.createInterface({
    input: process.stdin,
    output: process.stdout,
    prompt: "> ",
  });

  rl.prompt();

  rl.on("line", async (userInput: string) => {
    const trimmedInput = userInput.trim();

    if (["exit", "quit", "bye"].includes(trimmedInput.toLowerCase())) {
      console.log("\nGoodbye!");
      rl.close();
      process.exit(0);
    }

    if (!trimmedInput) {
      rl.prompt();
      return;
    }

    messages.push({ role: "user", content: trimmedInput });
    console.log("\nAgent is thinking...\n");

    try {
      const stream = streamText({
        model: openai("gpt-5"),
        messages,
        tools,
        toolChoice: "auto",
        stopWhen: stepCountIs(10),
        onStepFinish: (step) => {
          for (const toolCall of step.toolCalls) {
            console.log(`[Using tool: ${toolCall.toolName}]`);
          }
          if (step.toolCalls.length > 0) {
            console.log(""); // Add space after tool calls
          }
        },
      });

      for await (const chunk of stream.textStream) {
        process.stdout.write(chunk);
      }

      console.log("\n\n---\n");

      // Get final result for message history
      const response = await stream.response;
      if (response?.messages?.length) {
        messages.push(...response.messages);
      }
    } catch (error) {
      console.error("\nAn error occurred while talking to the agent:");
      console.error(error);
      console.log(
        "\nYou can try again or restart the app if it keeps happening.\n",
      );
    } finally {
      rl.prompt();
    }
  });

  rl.on("close", async () => {
    await mcpClient.close();
    console.log("\n👋 Session ended.");
    process.exit(0);
  });
}

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});

Conclusion

You've successfully built a Sevdesk agent using the Vercel AI SDK with streaming capabilities! This implementation provides a powerful foundation for building AI applications with natural language interfaces and real-time feedback.

Key features of this implementation:

  • Real-time streaming responses for a better user experience with typewriter effect
  • Live tool execution feedback showing which tools are being used as the agent works
  • Dynamic tool loading through Composio's Tool Router with secure authentication
  • Multi-step tool execution with configurable step limits (up to 10 steps)
  • Comprehensive error handling for robust agent execution
  • Conversation history maintenance for context-aware responses

You can extend this further by adding custom error handling, implementing specific business logic, or integrating additional Composio toolkits to create multi-app workflows.

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FAQ

What are the differences in Tool Router MCP and Sevdesk MCP?

With a standalone Sevdesk MCP server, the agents and LLMs can only access a fixed set of Sevdesk tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Sevdesk and many other apps based on the task at hand, all through a single MCP endpoint.

Can I use Tool Router MCP with Vercel AI SDK v6?

Yes, you can. Vercel AI SDK v6 fully supports MCP integration. You get structured tool calling, message history handling, and model orchestration while Tool Router takes care of discovering and serving the right Sevdesk tools.

Can I manage the permissions and scopes for Sevdesk while using Tool Router?

Yes, absolutely. You can configure which Sevdesk scopes and actions are allowed when connecting your account to Composio. You can also bring your own OAuth credentials or API configuration so you keep full control over what the agent can do.

How safe is my data with Composio Tool Router?

All sensitive data such as tokens, keys, and configuration is fully encrypted at rest and in transit. Composio is SOC 2 Type 2 compliant and follows strict security practices so your Sevdesk data and credentials are handled as safely as possible.

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