ProntoFax for Claude and ChatGPT

Updated October 13, 2026

ProntoFax publishes a Model Context Protocol server. Once you connect it, your assistant can look up fax numbers we have verified against the agency that published them, and open a send form inside the chat. It needs no account and no sign-in.

The short version: Connect ProntoFax to your assistant, ask for an agency fax number, and send the fax from a form that opens right in the chat.

What the assistant can do

lookup_fax_number: Finds a verified fax number for a state or federal agency and returns it with the official page it was read from and the date it was last checked. It returns nothing rather than guessing.
send_fax: Opens a form in the chat with the number already filled in. You add pages from your camera or a PDF, add a cover page if you want one, and pay. Nothing is sent until you finish paying. On an assistant that cannot show the form, you get a link to the same thing in your browser.

Your documents never pass through the assistant. You upload them to ProntoFax yourself, and nothing you upload is returned to the model.

Which agencies it covers

Only numbers we have read off the agency’s own website and keep checking. That is Social Security field offices in 56 states and territories, MassHealth, California EDD, Illinois IDES, NJ FamilyCare, IRS Form 2553, FEMA, the state unemployment agencies of Alabama, Colorado, Indiana, Iowa, Kentucky, Maryland, Missouri, New Jersey, New York, South Carolina, Texas, Wisconsin, and the state Medicaid agencies of Florida, Georgia, Idaho, Louisiana, Montana, Nebraska, New Mexico, Oregon, Texas, Utah, Washington.

Social Security and Medicaid publish no national fax number. Each Social Security field office and each state Medicaid agency has its own, so a lookup for either needs a city or a state.

Ask for any other agency and the assistant will tell you we have no verified number for it. That is deliberate. The number on the letter you received is more reliable than a guess.

Connect it in Claude

Open Settings, then Connectors.
Choose Add custom connector.
Paste https://mcp.prontofax.com/mcp and save.

Using ProntoFax in Claude as a user? See Fax from Claude.

Connect it in ChatGPT

Open Settings, then Security and login, and turn on Developer mode.
Go to chatgpt.com/plugins and choose the plus button.
Point it at https://mcp.prontofax.com/mcp and choose No Auth.

Connect it in Grok

Open grok.com/connectors.
Choose New Connector, then Custom.
Point it at https://mcp.prontofax.com/mcp with no auth.

Connect it in Muse

Ask Muse to build a custom integration to https://mcp.prontofax.com/mcp.
It needs no sign-in, so choose no auth if Muse asks.

ProntoFax is not listed in the Muse directory yet. Until it is, connect it this way. Muse shows no form in the chat, so send_fax answers with a link that opens the send page in your browser, with the number filled in.

Connect it in Grok Bot

Install ProntoFax from the Cursor marketplace once it is listed there.
Until then, open grok.com/connectors and add https://mcp.prontofax.com/mcp with no auth.

Grok Bot shows no form in the chat, so send_fax answers with a link that opens the send page in your browser, with the number filled in.

Connect it in Claude Code

claude mcp add --transport http prontofax https://mcp.prontofax.com/mcp

Things to try

What is the fax number for the Texas Workforce Commission?
Find the Social Security office fax number in Denver.
I need to fax my renewal forms to MassHealth.
Fax this to 857-323-8300.
Here is my letter. Send it to the fax number on it.

What the server receives

Only the arguments your assistant passes to a tool: the agency you asked about, a city or state, and a fax number when you give one. We do not receive your conversation, and we do not store what you typed.

We log which tool ran, which assistant called it, which agency matched, and whether it found anything. When an assistant connects, we also log the name and version it reports for itself. That is what tells us the integration is working.

No card details ever reach the server, and no document does either. Payment is handled by Stripe, and the full detail is in our Privacy Policy .

Getting help

Email support@prontofax.com if a number looks wrong or a lookup fails. If an agency has changed a number, tell us and we will check it against their site.