OpenAI's Codex CLI supports remote HTTP MCP servers directly from its TOML config - point it at OTPBox to give Codex a real inbox for signup and verification flows.
Mint a free key first (no account, no card):
curl -X POST https://otpbox.io/api/v1/keys/free -H "content-type: application/json" -d '{}'
→ { "id": "lic_...", "key": "...", "plan": "free", "quotaLimit": 200 }
Add to ~/.codex/config.toml:
[mcp_servers.otpbox] url = "https://otpbox.io/mcp" bearer_token_env_var = "OTPBOX_KEY"
OTPBOX_KEY as an environment variable before running codex - Codex reads the bearer token from it rather than storing the raw key in the config file.Once connected, Codex can call OTPBox's 13 MCP tools directly. For example:
"Create a disposable inbox with otpbox, sign up for this app using it, wait for the code, and finish verification."
Every code and link comes from a real delivered email, not a stub - so the test proves the actual signup flow works.
OTP codes and verification links are parsed out automatically. No regex against raw email bodies.
200 requests/month with a key minted in one call - no account, no payment info, no waiting.
create_test_inbox, wait_for_email, get_otp, get_verification_link, create_test_identity, and more - the full loop is agent-callable.
For Codex's own MCP setup UI/flags beyond the snippet above, see Codex's MCP documentation.