---
title: "WarmInboxes for AI Agents: MCP Server, Free API, JSON Specs"
description: "Deliverability checks an AI agent can call: an MCP server with 15 tools, a free HTTP API with no key, and machine-readable descriptions of both."
url: https://warminboxes.com/for-ai
breadcrumb: "Home > Free Tools > For AI Agents"
---
For machines

# WarmInboxes for AI agents

Everything here is callable without an account. 15 live deliverability checks over MCP or plain HTTP, and machine-readable descriptions of both. Ordering and running the infrastructure itself is a separate, authenticated API — the boundary is at the foot of this page.

## What an agent can do here

Every check queries live DNS, registries and blacklists at call time. Nothing is cached, and none of these endpoints store the domain or address you pass them.

| Check | MCP tool | HTTP endpoint | Parameters |
| --- | --- | --- | --- |
| Deliverability grade (A-F) | check_deliverability | check-deliverability | domain |
| SPF record | check_spf | check-spf | domain |
| DKIM record | check_dkim | check-dkim | domain, selector |
| DMARC record | check_dmarc | check-dmarc | domain |
| BIMI record | check_bimi | check-bimi | domain |
| MTA-STS policy | check_mta_sts | check-mta-sts | domain |
| DNS records | check_dns | check-dns | domain, type |
| Blacklist / RBL check | check_blacklist | check-blacklist | input |
| SURBL URI blacklist (bulk) | check_surbl | check-surbl | domains (comma-separated) |
| Nameservers and DNS provider (bulk) | check_nameservers | check-nameservers | domains (comma-separated) |
| Domain registration and expiry | check_domain_expiry | check-domain-expiry | domain |
| Google Workspace tenancy | check_google_domain | check-google-domain | domain |
| CNAME chain | check_cname | check-cname | host, expected |
| Email verification (bulk) | verify_email | verify-email | emails (comma-separated) |
| ESP segmentation (bulk) | segment_esp | segment-esp | domains (comma-separated) |

There are 33 tools on the site in total; the 15 above are the ones with an endpoint behind them. The rest run in the browser — [see all of them](https://warminboxes.com/deliverability-tools).

## MCP

Streamable HTTP, no authentication, no signup. Add it as a remote server and the checks appear as typed tools. A plain `GET` on the endpoint returns the server info and the tool list without a handshake, which is the quickest way to see what is there.
`{
 "mcpServers": {
 "warminboxes": {
 "url": "https://warminboxes.com/mcp"
 }
 }
}`
https://warminboxes.com/mcp

## HTTP API

Every check is also a plain endpoint. GET with query parameters or POST with a JSON body; both return JSON. No key, no signup, CORS open. Please be reasonable with volume — there is no rate-limit key to ask for, which only works while nobody abuses it.
`curl "https://warminboxes.com/.netlify/functions/check-deliverability?domain=stripe.com"`
Described in full at [/openapi.json](https://warminboxes.com/openapi.json).

## Machine-readable files

- [/llms.txt](https://warminboxes.com/llms.txt)What this site is, its pages, its tools and its API, as prose.
- [/llms-full.txt](https://warminboxes.com/llms-full.txt)Every page on the site as plain text, in one fetch.
- [/tools.json](https://warminboxes.com/tools.json)This table as JSON: each tool with its category, endpoint and MCP name.
- [/openapi.json](https://warminboxes.com/openapi.json)OpenAPI 3.1 for the free API, generated from the table that answers it.
- [/price.md](https://warminboxes.com/price.md)Every price, both products, every billing cycle.
- [/sitemap.xml](https://warminboxes.com/sitemap.xml)Every URL.

Every page also has a markdown twin: append `.md` to its URL.

## What needs authentication

Everything above

No key. Read-only: these look things up and change nothing.

The infrastructure API

Ordering inboxes and domains, and managing them. Bearer token, documented separately — do not infer its endpoints from the free ones.

[api.warminboxes.com/v1](https://api.warminboxes.com)[docs.warminboxes.com](https://docs.warminboxes.com)[its own llms.txt](https://docs.warminboxes.com/llms.txt)

## Appropriate use

These are the tools our own agency runs on, published so anyone can check a domain before sending to it. Use them to diagnose infrastructure you own or are working on. They are not for enumerating someone else's estate at volume, and the bulk endpoints exist so one caller can check their own list in a single request rather than hammering the single-domain ones.
[Browse the tools a human would use](https://warminboxes.com/deliverability-tools)