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

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

Supported Tools & Triggers

Tools
Update AssistantTool to update an existing Vapi assistant configuration.
List CallsTool to list calls from Vapi.
Delete ChatTool to delete a chat by its ID from Vapi.
Get ChatTool to fetch chat details by ID.
Create Analytics QueriesTool to create and execute analytics queries on VAPI data.
Create AssistantTool to create a new Vapi assistant with specified transcriber, voice, and AI model configurations.
Create EvalTool to create an eval for testing conversation flows.
Create OpenAI ChatTool to create an OpenAI-compatible chat using the Vapi API.
Create Phone NumberTool to create a phone number with Vapi.
Create Monitoring PolicyTool to create a monitoring policy in VAPI.
Create Provider ResourceTool to create an 11Labs pronunciation dictionary resource.
Create ScorecardTool to create a scorecard for observability and evaluation.
Delete CallTool to delete a call by its unique identifier.
Delete EvalTool to delete an eval by ID.
Delete Phone NumberTool to delete a phone number from Vapi.
Get EvalTool to retrieve an eval by its ID.
Delete Eval RunTool to delete an eval run by its ID from Vapi.
Update EvalTool to update an existing eval in Vapi.
Get AssistantTool to retrieve a specific assistant by ID from Vapi.
Get CallTool to fetch call details by ID.
Get FileTool to retrieve a file by its ID from Vapi.
Get InsightsTool to retrieve insights from Vapi.
List Monitoring PoliciesTool to retrieve monitoring policies from Vapi.
Get Observability ScorecardTool to list observability scorecards with optional filtering and pagination.
List Provider ResourcesTool to list provider resources from Vapi.
List Structured OutputsTool to list structured outputs with optional filtering.
Get InsightsTool to retrieve insights from VAPI.
List AssistantsTool to list all assistants in your VAPI organization.
List ChatsTool to retrieve a list of chat conversations from VAPI.
List EvalsTool to retrieve a paginated list of evals from Vapi.
List Provider ResourcesTool to retrieve provider resources from Vapi (e.
Update InsightTool to update an existing insight configuration in VAPI.
Create Phone NumberTool to create a phone number with VAPI.
List ScorecardsTool to retrieve a paginated list of scorecards from Vapi.
Create SessionTool to create a new session in Vapi.
List SessionsTool to retrieve a paginated list of sessions from VAPI.
List Structured OutputsTool to list structured outputs with optional filtering and pagination.
Get ToolTool to fetch tool details by ID.
Test Code Tool ExecutionTool to test TypeScript code execution in Vapi's code tool environment.
Update ToolTool to update an existing Vapi tool configuration.
Update Phone NumberTool to update an existing phone number configuration in VAPI.
Upload FileTool to upload a file to Vapi Knowledge Base.

Conclusion

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

How to build Vapi MCP Agent with another framework

FAQ

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

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

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

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

Used by agents from

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