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How to integrate Writer MCP with Mastra AI

Connect Mastra AI to Writer MCP. Summarize key findings from uploaded medical notes, generate chat responses using enterprise llm, and more using natural language, with authentication handled for you.

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Writer is an enterprise-grade generative AI platform for building and deploying custom LLM-powered applications. Get reliable content generation, advanced RAG, and built-in AI guardrails for secure, compliant workflows.

23 Tools

Introduction

This guide walks you through connecting Writer to Mastra AI using the Composio tool router. By the end, you'll have a working Writer agent that can generate text and chat completions, build and query knowledge graphs, parse PDFs, detect AI content, and translate text through natural language commands.

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

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

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TL;DR

Here's what you'll learn:
  • Set up your environment so Mastra, OpenAI, and Composio work together
  • Create a Tool Router session in Composio that exposes Writer tools
  • Connect Mastra's MCP client to the Composio generated MCP URL
  • Fetch Writer tool definitions and attach them as a toolset
  • Build a Mastra agent that can reason, call tools, and return structured results
  • Run an interactive CLI where you can chat with your Writer agent

What is Mastra AI?

Mastra AI is a TypeScript framework for building AI agents with tool support. It provides a clean API for creating agents that can use external services through MCP.

Key features include:

  • MCP Client: Built-in support for Model Context Protocol servers
  • Toolsets: Organize tools into logical groups
  • Step Callbacks: Monitor and debug agent execution
  • OpenAI Integration: Works with OpenAI models via @ai-sdk/openai

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

The Writer MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Writer account. It provides structured and secure access to your Writer AI platform, so your agent can perform actions like querying knowledge graphs, generating chat completions, extracting medical concepts, managing files, and orchestrating enterprise AI workflows on your behalf.

  • Conversational AI and content generation: Use your agent to generate chat-based completions and natural language responses using Writer's advanced LLMs.
  • Enterprise knowledge graph management: Create, retrieve, list, or delete knowledge graphs to organize and access structured knowledge within your organization.
  • Automated data extraction from clinical text: Extract medical entities and standardized codes (like SNOMED CT) from unstructured clinical or healthcare text for downstream analysis.
  • Application and model discovery: List available no-code agent applications and LLM models to streamline how your agent selects tools for specific tasks.
  • File management and inspection: Retrieve and review uploaded files, filter by attributes, and manage your enterprise content for further AI-driven actions.

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

Step by step09 STEPS
1

Prerequisites

Before starting, make sure you have:
  • Node.js 18 or higher
  • A Composio account with an active API key
  • An OpenAI API key
  • Basic familiarity with TypeScript
2

Getting API Keys for OpenAI and Composio

OpenAI API Key
  • Go to the OpenAI dashboard and create an API key.
  • You need credits or a connected billing setup to use the models.
  • Store the key somewhere safe.
Composio API Key
  • Log in to the Composio dashboard.
  • Go to Settings and copy your API key.
  • This key lets your Mastra agent talk to Composio and reach Writer through MCP.
3

Install dependencies

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

Install the required packages.

What's happening:

  • @composio/core is the Composio SDK for creating MCP sessions
  • @mastra/core provides the Agent class
  • @mastra/mcp is Mastra's MCP client
  • @ai-sdk/openai is the model wrapper for OpenAI
  • dotenv loads environment variables from .env
4

Set up environment variables

bash
COMPOSIO_API_KEY=your_composio_api_key_here
COMPOSIO_USER_ID=your_user_id_here
OPENAI_API_KEY=your_openai_api_key_here

Create a .env file in your project root.

What's happening:

  • COMPOSIO_API_KEY authenticates your requests to Composio
  • COMPOSIO_USER_ID tells Composio which user this session belongs to
  • OPENAI_API_KEY lets the Mastra agent call OpenAI models
5

Import libraries and validate environment

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

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

if (!openaiAPIKey) 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 as string,
});
What's happening:
  • dotenv/config auto loads your .env so process.env.* is available
  • openai gives you a Mastra compatible model wrapper
  • Agent is the Mastra agent that will call tools and produce answers
  • MCPClient connects Mastra to your Composio MCP server
  • Composio is used to create a Tool Router session
6

Create a Tool Router session for Writer

typescript
async function main() {
  const session = await composio.create(
    composioUserID as string,
    {
      toolkits: ["writer"],
    },
  );

  const composioMCPUrl = session.mcp.url;
  console.log("Writer MCP URL:", composioMCPUrl);
What's happening:
  • create spins up a short-lived MCP HTTP endpoint for this user
  • The toolkits array contains "writer" for Writer access
  • session.mcp.url is the MCP URL that Mastra's MCPClient will connect to
7

Configure Mastra MCP client and fetch tools

typescript
const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      nasdaq: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

console.log("Fetching MCP tools from Composio...");
const composioTools = await mcpClient.getTools();
console.log("Number of tools:", Object.keys(composioTools).length);
What's happening:
  • MCPClient takes an id for this client and a list of MCP servers
  • The headers property includes the x-api-key for authentication
  • getTools fetches the tool definitions exposed by the Writer toolkit
8

Create the Mastra agent

typescript
const agent = new Agent({
    name: "writer-mastra-agent",
    instructions: "You are an AI agent with Writer tools via Composio.",
    model: "openai/gpt-5",
  });
What's happening:
  • Agent is the core Mastra agent
  • name is just an identifier for logging and debugging
  • instructions guide the agent to use tools instead of only answering in natural language
  • model uses openai("gpt-5") to configure the underlying LLM
9

Set up interactive chat interface

typescript
let messages: AiMessageType[] = [];

console.log("Chat started! Type 'exit' or 'quit' to end.\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({
    id: crypto.randomUUID(),
    role: "user",
    content: trimmedInput,
  });

  console.log("\nAgent is thinking...\n");

  try {
    const response = await agent.generate(messages, {
      toolsets: {
        writer: composioTools,
      },
      maxSteps: 8,
    });

    const { text } = response;

    if (text && text.trim().length > 0) {
      console.log(`Agent: ${text}\n`);
        messages.push({
          id: crypto.randomUUID(),
          role: "assistant",
          content: text,
        });
      }
    } catch (error) {
      console.error("\nError:", error);
    }

    rl.prompt();
  });

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

main().catch((err) => {
  console.error("Fatal error:", err);
  process.exit(1);
});
What's happening:
  • messages keeps the full conversation history in Mastra's expected format
  • agent.generate runs the agent with conversation history and Writer toolsets
  • maxSteps limits how many tool calls the agent can take in a single run
  • onStepFinish is a hook that prints intermediate steps for debugging

Complete Code

Here's the complete code to get you started with Writer and Mastra AI:

typescript
import "dotenv/config";
import { openai } from "@ai-sdk/openai";
import { Agent } from "@mastra/core/agent";
import { MCPClient } from "@mastra/mcp";
import { Composio } from "@composio/core";
import * as readline from "readline";

import type { AiMessageType } from "@mastra/core/agent";

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

if (!openaiAPIKey) 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 as string });

async function main() {
  const session = await composio.create(composioUserID as string, {
    toolkits: ["writer"],
  });

  const composioMCPUrl = session.mcp.url;

  const mcpClient = new MCPClient({
    id: composioUserID as string,
    servers: {
      writer: {
        url: new URL(composioMCPUrl),
        requestInit: {
          headers: session.mcp.headers,
        },
      },
    },
    timeout: 30_000,
  });

  const composioTools = await mcpClient.getTools();

  const agent = new Agent({
    name: "writer-mastra-agent",
    instructions: "You are an AI agent with Writer tools via Composio.",
    model: "openai/gpt-5",
  });

  let messages: AiMessageType[] = [];

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

  rl.prompt();

  rl.on("line", async (input: string) => {
    const trimmed = input.trim();
    if (["exit", "quit"].includes(trimmed.toLowerCase())) {
      rl.close();
      return;
    }

    messages.push({ id: crypto.randomUUID(), role: "user", content: trimmed });

    const { text } = await agent.generate(messages, {
      toolsets: { writer: composioTools },
      maxSteps: 8,
    });

    if (text) {
      console.log(`Agent: ${text}\n`);
      messages.push({ id: crypto.randomUUID(), role: "assistant", content: text });
    }

    rl.prompt();
  });

  rl.on("close", async () => {
    await mcpClient.disconnect();
    process.exit(0);
  });
}

main();

Conclusion

You've built a Mastra AI agent that can interact with Writer through Composio's Tool Router. You can extend this further by:
  • Adding other toolkits like Gmail, Slack, or GitHub
  • Building a web-based chat interface around this agent
  • Using multiple MCP endpoints to enable cross-app workflows
TOOLS

Supported Tools

Every Writer action and event your agent gets out of the box.

Add File to Knowledge Graph

Tool to add a file to a knowledge graph for indexing and retrieval.

Analyze Images

Tool to analyze images using Writer's vision capabilities.

Ask Question to Knowledge Graph

Send a question to specified Knowledge Graphs, with optional context.

Chat Completion

Generate a non-streaming chat completion from a conversation history using a specified model.

Create Knowledge Graph

Create an empty Knowledge Graph that files can be added to.

Delete File

Tool to delete a file by its ID.

Delete Graph

Tool to delete a knowledge graph by its ID.

Detect AI Content

Analyze text for AI-generated content and return a classification label and score.

Download File

Tool to download the binary content of a file.

Get File

Tool to retrieve detailed information about a specific file by its ID.

List Applications

List a page of no-code agent applications, with an optional page size and cursor for retrieving subsequent pages.

List Files

Tool to list all uploaded files.

List Knowledge Graphs

List a page of Writer Knowledge Graphs.

List Models

Tool to list all available language models.

Medical Text Comprehension

Extract medical entities and any returned concepts from unstructured clinical text using the Entities response type.

Parse PDF

Parse a previously uploaded PDF into text or markdown using Writer's deprecated PDF parser endpoint, which Writer scheduled for removal on December 22, 2025.

Remove File From Graph

Tool to remove a file from a Knowledge Graph.

Retrieve Knowledge Graph

Retrieve a Writer Knowledge Graph by its ID to inspect details of an existing graph, such as its name, description, creation time, and file processing status.

Text Generation

Tool to generate text based on a given prompt.

Translate Text

Tool to translate text from one language to another with support for formality, length control, and profanity masking.

Update Knowledge Graph

Tool to update an existing knowledge graph.

Upload File

Submit a file to Writer using a multipart upload for file-based operations.

Web Search

Tool to perform a web search.

FRAMEWORKS

How to build Writer MCP Agent with another framework

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Claude Code

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Claude Cowork

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OpenAI Agents SDK logo

OpenAI Agents SDK

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Claude Agent SDK logo

Claude Agent SDK

Use Writer MCP with Claude Agent SDK

Codex logo

Codex

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OpenClaw logo

OpenClaw

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Hermes logo

Hermes

Use Writer MCP with Hermes

Atomic Agent logo

Atomic Agent

Use Writer MCP with Atomic Agent

Google ADK logo

Google ADK

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LangChain logo

LangChain

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Vercel AI SDK logo

Vercel AI SDK

Use Writer MCP with Vercel AI SDK

LlamaIndex logo

LlamaIndex

Use Writer MCP with LlamaIndex

CrewAI logo

CrewAI

Use Writer MCP with CrewAI

Pydantic AI logo

Pydantic AI

Use Writer MCP with Pydantic AI

AutoGen logo

AutoGen

Use Writer MCP with AutoGen

FAQ

Frequently asked questions

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

Yes, you can. Mastra AI 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 Writer tools.

Yes, absolutely. You can configure which Writer 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.

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 Writer data and credentials are handled as safely as possible.

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