PromptFax

app.promptfaxPublished by promptfax.appOfficial publisherv0.1.0Updated Oct 24, 2026

Send a one-off fax from inside ChatGPT or Claude. Pay-per-use, $2-$4.50 per delivered fax.

VerifiedStreamable HTTPWeb executableCommunication & CollaborationBusiness & Commerce

Overview

AI-generated overview

PromptFax lets an AI assistant prepare, price and send one-off outbound faxes, with a user-reviewed quote and Stripe payment before transmission.

What you can do
Start a fax session and attach documents, either a PromptFax document or HTTPS PDF links, before pricing anything. Create a user-reviewable pay-per-use quote for a fax number and chosen documents. Open Stripe Checkout once the user accepts the quote, then send the fax after payment is authorized. Check workflow, quote, payment and transmission status, retry a failed fax under the existing authorization with an optional corrected destination, or cancel the active send.
When to use it
Useful when someone needs to send an occasional one-off fax from a chat assistant and is willing to pay per delivered fax, rather than signing up for a fax service. It suits irregular sending where each job should be quoted and paid for individually.
Requirements
A remote MCP endpoint at promptfax.app over streamable HTTP; no package, environment variable or header is declared. Sending requires a Stripe payment authorization and a destination fax number, plus documents as a PromptFax document or HTTPS PDF URLs.
Before you install
Every real send costs money, quoted at $2 to $4.50 per delivered fax, and requires Stripe payment authorization; payment truth is the webhook-confirmed authorization, not the browser redirect. Sending, retrying and cancelling change real outbound state, so confirm the destination number and documents with the user first. Documents are uploaded to PromptFax as a third party.

Installation

In SourceWeft

  1. Open PromptFax in the dashboard and add it to a workspace.
  2. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/app.promptfax%2Fpromptfax/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config.

{
  "mcpServers": {
    "promptfax": {
      "type": "http",
      "url": "https://promptfax.app/mcp"
    }
  }
}

Tools

8

start_session

Start PromptFax session

Use this first when a user wants to send or price a fax. PromptFax is built for irregular, pay-per-use outbound faxing: every real send requires a user-reviewed quote and Stripe payment authorization before transmission. MCP clients should set hostType to identify their host: chatgpt, claude, browser, or other. In ChatGPT, pass official files[] file parameters first when they are available so PromptFax can immediately import files[].download_url; never pass a raw file_id or local path as the document. The ChatGPT widget opens for destination entry, automatic quote creation, Stripe Checkout, status tracking, and Choose PDF from ChatGPT fallback when automatic attachment is unavailable or fails. If no document is attached, tell the user to attach a document in the widget. The widget does not provide a document preview step. Do not tell ChatGPT users to get a quote; after the widget has a document and valid destination, tell them to verify the price and use Pay & send when ready. Standards-compatible MCP Apps hosts use the inline PromptFax picker, and text-only clients use the hosted PromptFax session page or attach_document with a fetchable HTTPS URL. Do not call get_quote, checkout, or send_fax for a ChatGPT widget session unless the user explicitly asks for fallback behavior or the widget is unavailable. Use get_status only for a textual status refresh.

ParametersfileshostTypemetadatafaxNumbersessionIdhostCapabilities

attach_document

Attach fax document

Fallback/non-widget tool for binding a PromptFax document or one or more HTTPS PDF URLs into the current MCP session before requesting a quote. In ChatGPT widget sessions, prefer the widget's file controls after start_session instead of calling this tool unless the widget is unavailable or the user explicitly asks for fallback behavior.

ParametersfileUrlssessionIdrequireddocumentId

get_quote

Get fax quote

Fallback/non-widget tool for creating a user-reviewable pay-per-use fax quote when you have a fax number and either an MCP session, a PromptFax documentId, or one or more HTTPS PDF URLs. A quote is required before Stripe Checkout and before any real fax transmission. In ChatGPT widget sessions, do not call this after start_session because the widget auto-quotes once the document and destination are ready.

ParametersfileUrlsfaxNumbersessionIddocumentId

checkout

Open Stripe Checkout

Fallback/non-widget tool for starting external Stripe Checkout after the user accepts a pay-per-use quote. Payment authorization is required before PromptFax can send; PromptFax treats webhook-confirmed authorization, not browser redirect, as payment truth. In ChatGPT widget sessions, do not call this after start_session because the widget's Pay & send step opens Checkout.

ParameterssessionIdsendIntentIdautoSendAfterAuthorization

send_fax

Send paid fax

Fallback/non-widget tool for sending after payment is authorized and the user explicitly wants to send now. In ChatGPT widget sessions, do not call this after start_session unless the widget is unavailable or the user explicitly asks for fallback behavior.

ParameterssessionIdsendIntentId

get_status

Get fax status

Use this when you need the latest PromptFax workflow state, quote/payment state, or fax transmission status.

ParameterssessionIdsendIntentId

retry_failed_fax

Retry failed fax

Use this after a retry-eligible failed fax to queue another attempt under the existing authorization. You may supply a corrected destination.

ParametersfaxNumbersessionIdsendIntentId

cancel

Cancel fax send

Use this when you need to cancel the active PromptFax send.

ParameterssessionIdsendIntentId

Version history

1
  1. v0.1.0LatestSep 16, 2026

Score

83% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listedRequired15 pts
  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts

    Declare a GitHub repository with a README, or serve resource_documentation in the OAuth protected-resource metadata.

  • LicenseNot applicable

    A hosted service is used under its provider's terms, so no license is expected here. This check is left out of the percentage.