An AI agent driving a browser to sign up for a service hits the same wall a human does: "check your email for a code." Unlike a human, it has no inbox to check — unless you give it one. OTPBox's MCP server does exactly that: it hands the agent tools to create a real inbox, wait for mail, and pull out the code or link, all inside the same conversation that's driving the signup.
The Playwright/Cypress guides in this series wire a fixed sequence of steps a human wrote in advance. An agent is different: it decides at runtime whether it needs an inbox, when to check it, and what to do with what arrives. MCP tools are built for exactly that — single, well-scoped calls the agent's own reasoning invokes as needed, rather than a script it executes top to bottom. The same OTPBox account and quota back both; MCP is just a second interface onto the same inboxes, messages and identities as the REST API.
OTPBox runs a remote (streamable HTTP) MCP server at https://otpbox.io/mcp, authenticated with the same bearer key as the REST API. Add it to an MCP-aware client — Claude, Cursor, or your own agent harness:
{
"mcpServers": {
"otpbox": {
"url": "https://otpbox.io/mcp",
"headers": { "Authorization": "Bearer <your-key>" }
}
}
}Get a key with no account at all — POST /api/v1/keys/free (see Get a key) — or mint an organization key from the dashboard if several agents or projects should share one pooled quota.
The server exposes 13 tools total; these are the ones a signup-and-verify task actually uses. Full list and argument details are in the docs.
| Tool | Use it to… |
|---|---|
create_test_inbox | Get a fresh disposable address before starting the signup. |
wait_for_email | Block until something arrives, instead of the agent looping on its own. |
get_otp | Read just the extracted code from the most recent message. |
get_verification_link | Read the extracted confirmation/reset/magic-login link instead of a code. |
get_latest_email | Read the full message when the agent needs more than the code (subject, body, sender). |
create_test_identity | Get a name, country and profile alongside the inbox, for a signup form that wants a believable person, not just an email address. |
delete_inbox | Clean up once the task is done. |
Prompted with something like "sign up for acme.example.com and confirm the account exists," an agent with the OTPBox tools available and a browser tool (or its own HTTP capability) tends to sequence roughly like this — this is the tool-call pattern, not literal code, since the agent's own model decides the order and any retries:
1. create_test_inbox()
-> { id: "a1b2c3", address: "bold.quartz844@otpbox.io", expiresAt: ... }
2. (drive the browser) fill the signup form's email field with that address,
submit
3. wait_for_email({ inboxId: "a1b2c3", timeoutSeconds: 20 })
-> { timedOut: false, message: { code: "482913", ... } }
// or, if the agent only wants the code and not the whole message:
get_otp({ inboxId: "a1b2c3" })
-> { code: "482913", messageId: "msg_..." }
4. (drive the browser) type "482913" into the OTP field, submit
5. delete_inbox({ inboxId: "a1b2c3" })Prefer wait_for_email over having the agent call get_otp in a manual retry loop — it's one tool call that blocks server-side (up to 25 seconds) instead of several calls each burning a unit of quota.
An agent tasked with something like "create 10 test accounts with different countries and confirm each one verifies" can reach for create_bulk_test_identities (template plus a count of 1–50) instead of calling create_test_inbox in a loop — each identity comes back with a name, email and country-appropriate profile already attached, backed by its own real inbox. Templates: us_customer, indian_customer, european_customer, business_customer, student, employee.
Ready to wire this into your own agent? Create a free account
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