OpenAI Codex MCP Setup | Spec This Docs

Prerequisites

OpenAI Codex CLI or IDE extension installed
A Spec This account (you must be logged in via browser for OAuth)

Step 1: Add Spec This MCP Server

Add the following to your ~/.codex/config.toml file:

[mcp_servers.spec-this]
type = "http"
url = "http://localhost:3000/api/mcp"

Important: Use mcp_servers (with underscore, not hyphen).

Optional: Advanced Configuration

You can customize timeout settings if needed:

[mcp_servers.spec-this]
type = "http"
url = "http://localhost:3000/api/mcp"
startup_timeout = 10
tool_timeout = 60

startup_timeout - Time in seconds to wait for server startup (default: 10)
tool_timeout - Time in seconds to wait for tool responses (default: 60)

Configuration File Location

The Codex configuration file is located at:

macOS/Linux: ~/.codex/config.toml
Windows: %USERPROFILE%\.codex\config.toml

Note: Configuration is shared between the CLI and the IDE extension.

Step 2: Verify Connection

After adding the configuration:

Restart Codex or reload your IDE
The MCP server should connect automatically using your browser OAuth session
Test the connection by asking Codex:
"Can you list my Spec This plans?"

Official Documentation

For more details on Codex MCP configuration, see the Codex MCP Documentation.