How to integrate Outlook MCP with Codex

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Introduction

Codex is one of the most popular coding harnesses out there. And MCP makes the experience even better. With Outlook MCP integration, you can draft, triage, summarise emails, and much more, all without leaving the terminal or app, whichever you prefer.

Composio removes the Authentication handling completely from you. We handle the entire integration lifecycle, and all you need to do is just copy the URL below, authenticate inside Codex, and start using it.

Why use Composio?

Apart from a managed and hosted MCP server, you will get:

  • CodeAct: A dedicated workbench that allows GPT to write its code to handle complex tool chaining. Reduces to-and-fro with LLMs for frequent tool calling.
  • Large tool responses: Handle them to minimise context rot.
  • Dynamic just-in-time access to 20,000 tools across 870+ other Apps for cross-app workflows. It loads the tools you need, so GPTs aren't overwhelmed by tools you don't need.

How to install Outlook MCP in Codex

Codex CLI

Run the command in your terminal.

Terminal

This will auto-redirect you to the Rube authentication page.

Rube authentication redirect page

Once you're authenticated, you will be able to access the tools.

Verify the installation by running:

codex mcp list

If you otherwise prefer to use config.toml, add the following URL to it. You can get the bearer token from rube.app → Use Rube → MCP URL → Generate token

[projects."/home/user/composio"]
trust_level = "untrusted"

[mcp_servers.rube]
bearer_token_env_var = "your bearer token"
enabled = true
url = "https://rube.app/mcp"

Codex in VS Code

If you have installed Codex in VS Code.

Then: ⚙️ → MCP Settings → + Add servers → Streamable HTTP:

Add the Rube MCP URL: https://rube.app/mcp and the bearer token.

VS Code MCP Settings

To verify, click on the Open config.toml

Open config toml in Codex

Make sure it's there:

[mcp_servers.composio_rube]
bearer_token_env_var = "your bearer token"
enabled = true
url = "https://rube.app/mcp"

Codex App

Codex App follows the same approach as VS Code.

  1. Click ⚙️ on the bottom left → MCP Servers → + Add servers → Streamable HTTP:
Codex App MCP Settings
  1. Restart and verify if it's there in .codex/config.toml
[mcp_servers.composio_rube]
bearer_token_env_var = "your bearer token"
enabled = true
url = "https://rube.app/mcp"
  1. Save, restart the extension, and start working.

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

The Outlook MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Outlook account. It provides structured and secure access to your email, calendar, and contacts, so your agent can perform actions like sending emails, organizing folders, managing your calendar, and handling attachments on your behalf.

  • Email organization and folder management: Let your agent create, delete, or organize mail folders to keep your inbox tidy and efficient.
  • Calendar and event creation: Easily have your agent set up new calendars, so you can organize meetings and events without lifting a finger.
  • Smart attachments handling: Automatically download files from your emails or add attachments to outgoing messages for seamless file management.
  • Automated rules and filtering: Direct your agent to create email rules that filter, sort, or take action on messages as they arrive.
  • Contact and category organization: Ask your agent to create new contact folders or master categories to streamline how you manage people and projects.

Supported Tools & Triggers

Tools
Triggers
Add mail attachmentTool to add an attachment to an email message.
Create calendarTool to create a new calendar in the signed-in user's mailbox.
Create contact folderTool to create a new contact folder in the user's mailbox.
Create Email RuleCreate email rule filter with conditions and actions
Create mail folderTool to create a new mail folder.
Create master categoryTool to create a new category in the user's master category list.
Delete mail folderDelete a mail folder from the user's mailbox.
Download Outlook attachmentDownloads a specific file attachment from an email message in a microsoft outlook mailbox; the attachment must contain 'contentbytes' (binary data) and not be a link or embedded item.
Get mailbox settingsTool to retrieve mailbox settings.
Get mail deltaTool to retrieve incremental changes (delta) of messages in a mailbox.
Get mail tipsTool to retrieve mail tips such as automatic replies and mailbox full status.
Get master categoriesTool to retrieve the user's master category list.
Get supported languagesTool to retrieve supported languages in the user's mailbox.
Get supported time zonesTool to retrieve supported time zones in the user's mailbox.
List Outlook calendarsTool to list calendars in the signed-in user's mailbox.
List event attachmentsTool to list attachments for a specific outlook calendar event.
List Outlook attachmentsLists metadata (like name, size, and type, but not `contentbytes`) for all attachments of a specified outlook email message.
List event remindersTool to retrieve reminders for events occurring within a specified time range.
Add event attachmentAdds an attachment to a specific outlook calendar event.
Create Calendar EventCreates a new outlook calendar event, ensuring `start datetime` is chronologically before `end datetime`.
Create contactCreates a new contact in a microsoft outlook user's contacts folder.
Create email draftCreates an outlook email draft with subject, body, recipients, and an optional attachment.
Create a draft replyCreates a draft reply in the specified user's outlook mailbox to an existing message (identified by a valid `message id`), optionally including a `comment` and cc/bcc recipients.
Delete ContactPermanently deletes an existing contact, using its `contact id` (obtainable via 'list user contacts' or 'get contact'), from the outlook contacts of the user specified by `user id`.
Delete Calendar EventDeletes an existing calendar event, identified by its unique `event id`, from a specified user's microsoft outlook calendar, with an option to send cancellation notifications to attendees.
Get contactRetrieves a specific outlook contact by its `contact id` from the contacts of a specified `user id` (defaults to 'me' for the authenticated user).
Get contact foldersTool to retrieve a list of contact folders in the signed-in user's mailbox.
Get calendar eventRetrieves the full details of a specific calendar event by its id from a user's outlook calendar, provided the event exists.
Get email messageRetrieves a specific email message by its id from the specified user's outlook mailbox.
Get Outlook profileRetrieves the microsoft outlook profile for a specified user.
Get scheduleRetrieves free/busy schedule information for specified email addresses within a defined time window.
List Outlook contactsRetrieves a user's microsoft outlook contacts, from the default or a specified contact folder.
List eventsRetrieves events from a user's outlook calendar via microsoft graph api, supporting pagination, filtering, property selection, sorting, and timezone specification.
List mail foldersTool to list a user's top-level mail folders.
List MessagesRetrieves a list of email messages from a specified mail folder in an outlook mailbox, with options for filtering (including by conversationid to get all messages in a thread), pagination, and sorting; ensure 'user id' and 'folder' are valid, and all date/time strings are in iso 8601 format.
Move message to folderMove a message to another folder within the specified user's mailbox.
Reply to EmailSends a plain text reply to an outlook email message, identified by `message id`, allowing optional cc and bcc recipients.
Search Outlook messagesSearches messages in a microsoft 365 or enterprise outlook account mailbox, supporting filters for sender, subject, attachments, pagination, and sorting by relevance or date.
Send emailSends an email with subject, body, recipients, and an optional attachment via microsoft graph api; attachments require a non-empty file with valid name and mimetype.
Update calendar eventUpdates specified fields of an existing outlook calendar event.
Update ContactUpdates an existing outlook contact, identified by `contact id` for the specified `user id`, requiring at least one other field to be modified.
Update email messageUpdates specified properties of an existing email message; `message id` must identify a valid message within the specified `user id`'s mailbox.
Update mailbox settingsTool to update mailbox settings for the signed-in user.

Conclusion

You've successfully integrated Outlook with Codex using Composio's Rube MCP server. Now you can interact with Outlook directly from your terminal, VS Code, or the Codex App using natural language commands.

Key benefits of this setup:

  • Seamless integration across CLI, VS Code, and standalone app
  • Natural language commands for Outlook operations
  • Managed authentication through Composio's Rube
  • Access to 20,000+ tools across 870+ apps for cross-app workflows
  • CodeAct workbench for complex tool chaining

Next steps:

  • Try asking Codex to perform various Outlook operations
  • Explore cross-app workflows by connecting more toolkits
  • Build automation scripts that leverage Codex's AI capabilities

How to build Outlook MCP Agent with another framework

FAQ

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

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

Can I use Tool Router MCP with Codex?

Yes, you can. Codex 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 Outlook tools.

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

Yes, absolutely. You can configure which Outlook 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 Outlook data and credentials are handled as safely as possible.

Used by agents from

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Letta
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Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
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Context
Letta
glean
HubSpot
Agent.ai
Altera
DataStax
Entelligence
Rolai

Never worry about agent reliability

We handle tool reliability, observability, and security so you never have to second-guess an agent action.