How to integrate Heyy 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 Heyy 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 Heyy 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 Heyy MCP server, and what's possible with it?

The Heyy MCP server is an implementation of the Model Context Protocol that connects your AI agent and assistants like Claude, Cursor, etc directly to your Heyy account. It provides structured and secure access so your agent can perform Heyy operations on your behalf.

Supported Tools & Triggers

Tools
Create Contact AttributeTool to create a new custom attribute for contacts in Heyy.
Create ContactTool to create a new contact in Heyy with optional details including first name, last name, email, phone number, labels, and custom attributes.
Create LabelTool to create a new label for categorizing contacts in Heyy.
Create WebhookTool to create a new webhook for receiving event notifications across multiple channels.
Delete AttributeTool to delete an attribute by its unique identifier.
Delete LabelTool to delete a label by its unique identifier.
Delete WebhookTool to delete a webhook by its unique identifier.
List AttributesTool to retrieve all attributes available in the Heyy system.
List AutomationsTool to retrieve automation workflows for a specified channel.
List ChannelsTool to retrieve all available channels from the Heyy system.
List Message TemplatesTool to retrieve all message templates available in the Heyy system.
List API WebhooksTool to retrieve all API webhooks configured for the account.
Update WebhookTool to update a webhook's URL and active status.

Conclusion

You've successfully integrated Heyy with Codex using Composio's Rube MCP server. Now you can interact with Heyy 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 Heyy 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 Heyy operations
  • Explore cross-app workflows by connecting more toolkits
  • Build automation scripts that leverage Codex's AI capabilities

How to build Heyy MCP Agent with another framework

FAQ

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

With a standalone Heyy MCP server, the agents and LLMs can only access a fixed set of Heyy tools tied to that server. However, with the Composio Tool Router, agents can dynamically load tools from Heyy 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 Heyy tools.

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

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

Used by agents from

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