Connect ChatGPT and OpenAI agents

The server URL is https://app.lobbystack.com/api/mcp. Replace app.lobbystack.com with your own domain if you self-host. ChatGPT connects to it from the internet, so a self-hosted LobbyStack needs a public HTTPS address. See MCP server for the tools each permission unlocks.

ChatGPT

ChatGPT connects custom MCP servers from its Plugins page on the web. On Business, Enterprise and Edu plans, ChatGPT can use every LobbyStack tool, including the ones that change data. On Pro, it can only use tools that read data. In a Business workspace, only admins and owners can add a custom server. Enterprise and Edu admins can give that permission to other members.

Add the server

In ChatGPT, go to Plugins, click +, then Add custom MCP server. Name it LobbyStack and paste the server URL under Connection. You don’t need to turn on developer mode first.

Choose OAuth

Choose OAuth for authentication and leave any client ID and secret empty, because ChatGPT registers itself with LobbyStack. Read the risk warning, select I understand and want to continue, and click Create as a plugin.

ChatGPT opens LobbyStack. Sign in, pick the workspace, uncheck anything ChatGPT shouldn’t do, and click Allow access.

Install the plugin

Review the tools ChatGPT found, then install the plugin. In a new chat, type @ and select LobbyStack.

To disconnect, go to Settings > API keys in LobbyStack and click Disconnect next to ChatGPT under MCP connections.

OpenAI Responses API

The Responses API calls remote MCP servers for you. Pass an API key in headers:

curl https://api.openai.com/v1/responses \
  -H "Authorization: Bearer $OPENAI_API_KEY" \
  -H "content-type: application/json" \
  -d '{
    "model": "gpt-6-luna",
    "tools": [{
      "type": "mcp",
      "server_label": "lobbystack",
      "server_url": "https://app.lobbystack.com/api/mcp",
      "headers": { "Authorization": "Bearer '"$LOBBYSTACK_API_KEY"'" },
      "require_approval": "always"
    }],
    "input": "Who called yesterday and asked for a callback?"
  }'

require_approval: "always" makes the API stop before each tool call so your code can confirm it. Loosen it only for keys with read scopes.

Codex

The ChatGPT desktop app, the Codex CLI and the Codex IDE extension share one MCP configuration, so you add LobbyStack once. Add the server, then sign in:

codex mcp add lobbystack --url https://app.lobbystack.com/api/mcp
codex mcp login lobbystack

codex mcp login opens LobbyStack in your browser. Sign in, pick the workspace, uncheck anything Codex shouldn’t do, and click Allow access. Codex registers itself with LobbyStack, so you don’t need a client ID or secret. Then ask Codex to call get_business to check the connection.

Codex with an API key

To use an API key instead, add LobbyStack to ~/.codex/config.toml. Codex reads the key from the environment variable you name:

~/.codex/config.toml

[mcp_servers.lobbystack]
url = "https://app.lobbystack.com/api/mcp"
bearer_token_env_var = "LOBBYSTACK_API_KEY"

Export LOBBYSTACK_API_KEY in your shell before you start Codex.

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Self-hosting

Connect ChatGPT and OpenAI agents

ChatGPT

OpenAI Responses API

Codex

Codex with an API key

​ChatGPT

​OpenAI Responses API

​Codex

​Codex with an API key

ChatGPT

OpenAI Responses API

Codex

Codex with an API key