# PromptFax (remote · promptfax.app)

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

- Trust score: 78/100 (medium)
- Change this week: +18
- Registry status: active
- Liveness: live
- Owner verified: no
- Last scored: 2026-08-03

## Components

- remote · `promptfax.app`: 78/100 (this document), [markdown](https://verifymcp.io/servers/app-promptfax-promptfax/promptfax.md), [page](https://verifymcp.io/servers/app-promptfax-promptfax/promptfax)

## Channel facts

- Endpoint: `https://promptfax.app/mcp`
- Transports: `streamable-http`
- Auth: `none`
- Version: `0.1.0`

## Trust breakdown

How this component scores in each security and reliability category. Every signal is checked automatically against the live server, and we only credit what we can confirm. Scores are 0–100 per category. Scoring method: https://verifymcp.io/docs/scoring (what has changed: https://verifymcp.io/docs/scoring/changelog)

Scored 2026-08-03.

- **Endpoint Security**: 91/100
  - The endpoint's TLS certificate is valid, in date, and uses a strong key.
  - Authorisation is enforced on tool calls, advertised via RFC 9728 protected-resource metadata. Discovery is public, which costs nothing: no tool can be invoked without a token.
  - HTTPS is enforced; there's no plaintext access path.
  - HSTS check failed: the Strict-Transport-Security header is absent.
  - DNSSEC is configured correctly; the domain's records validate against the full chain to the root.
  - The authorisation server offers only Dynamic Client Registration (RFC 7591), which MCP 2026-07-28 deprecated in favour of Client ID Metadata Documents.
- **Transport & Reachability**: 100/100
  - Verified streamable-http transport via a live MCP handshake.
- **Schema Quality & AI Usability**: 62/100
  - AI-judged instruction clarity (good).
  - Context-footprint check failed: tool/resource definitions use about 1376 tokens (~172/item across 8 items; 8 tools + 0 resources), over budget; trim descriptions and params.
  - Usage-examples check failed: none of the tools include examples.
- **Stability & Change Management**: 27/100
  - Stability observed for 8 of 30 days with no destabilising changes; credit accrues until the full window elapses.
- **Tool Coverage**: 100/100
  - 100% of tools have a non-trivial description (not blank, and not just the tool's name).
  - 100% of tool parameters carry a description.
  - Structured output schemas are declared (100% of tools); any adoption earns full credit.
- **Capabilities**: 100/100
  - Implements a supported MCP spec version (2025-11-25); the latest is 2026-07-28.

## Install

### Claude

```bash
claude mcp add --transport http app-promptfax-promptfax https://promptfax.app/mcp
```

### Codex

```toml
[mcp_servers.app-promptfax-promptfax]
url = "https://promptfax.app/mcp"
```

### opencode

```json
{
  "$schema": "https://opencode.ai/config.json",
  "mcp": {
    "app-promptfax-promptfax": {
      "type": "remote",
      "url": "https://promptfax.app/mcp",
      "enabled": true
    }
  }
}
```

### OpenClaw

```bash
openclaw mcp add app-promptfax-promptfax --url https://promptfax.app/mcp --transport streamable-http
```

### Hermes

```yaml
mcp_servers:
  app-promptfax-promptfax:
    url: "https://promptfax.app/mcp"
```

### Other

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

The mcpServers block is a cross-client convention. Remote transports vary, so check your client's docs.

## Changelog

Every change recorded for this component, newest first. Days that predate change tracking, or that we cannot explain, say so: "we were watching and nothing happened" and "we were not watching" are different claims.

### 2026-08-03 (score 78, +1)

No change was recorded against any check on this day. Stability & Change Management went from 23 to 27. That category is still filling its 30-day observation window: 7 days of observed history at the previous scan, 8 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-08-01 (score 77, +43)

- [security improvement] Authorization: unverified → pass
- [functional improvement] MCP protocol: unverified → pass
- [functional improvement] Stability: unverified → 0.20
- [functional improvement] Tool coverage: unverified → 100

### 2026-07-31 (score 34, −37)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-07-30 (score 71, 0)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-07-29 (score 71, +1)

No change was recorded against any check on this day. Stability & Change Management went from 7 to 10. That category is still filling its 30-day observation window: 2 days of observed history at the previous scan, 3 at this one. The score rises as the window fills, whether or not the server changes.

### 2026-07-28 (score 70, +10)

- [security improvement] Transport: fail → pass

### 2026-07-27 (score 60, −9)

- [functional] We updated how we score, so this day's move reflects our rubric, not a change to the server

### 2026-07-26 (score 69)

First indexed and scored.

## MCP tools (8)

### `start_session` (~473 tokens)

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. When calling this from ChatGPT, set hostType to chatgpt so PromptFax uses the ChatGPT widget and file flow. In ChatGPT, this opens the PromptFax widget; after the widget is shown, let the widget handle file selection, destination entry, automatic quote creation, Stripe Checkout, and status tracking. 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. For Claude and other MCP hosts that cannot pass files directly, use the agent-friendly hosted PromptFax session page to guide upload/review, request a quote, launch Stripe Checkout, and poll delivery status. 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.

Input parameters:

- `faxNumber` (string): Destination US fax number. Accepts common human formats such as 415-555-0182 or E.164 format such as +14155550182.
- `files` (array): Optional host-supplied files for initial attachment. ChatGPT may provide temporary download URLs in files[].download_url.
- `hostCapabilities` (object): Optional host capability hints, such as whether the client supports widgets, file-picking, hosted links, or other interactive surfaces.
- `hostType` (string): Identify the MCP host so PromptFax can choose the right interaction mode. Use chatgpt for ChatGPT, claude for Claude, browser for a browser-hosted app, or other for unknown clients.
- `metadata` (object): Optional host-specific metadata for diagnostics or session continuity.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `attach_document` (~144 tokens)

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.

Input parameters:

- `documentId` (string): PromptFax document identifier created by a prior upload or hosted session.
- `fileUrls` (array): One or more HTTPS URLs for PDF or image documents that PromptFax should attach to the fax workflow.
- `sessionId` (string, required): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `get_quote` (~204 tokens)

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.

Input parameters:

- `documentId` (string): PromptFax document identifier created by a prior upload or hosted session.
- `faxNumber` (string): Destination US fax number. Accepts common human formats such as 415-555-0182 or E.164 format such as +14155550182.
- `fileUrls` (array): One or more HTTPS URLs for PDF or image documents that PromptFax should attach to the fax workflow.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `checkout` (~172 tokens)

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.

Input parameters:

- `autoSendAfterAuthorization` (boolean): When true, PromptFax sends automatically after Stripe confirms payment authorization. When false, call send_fax after authorization.
- `sendIntentId` (string): PromptFax send intent identifier returned by get_quote or session status. Use this for checkout, send, status, retry, or cancel operations.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `send_fax` (~119 tokens)

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.

Input parameters:

- `sendIntentId` (string): PromptFax send intent identifier returned by get_quote or session status. Use this for checkout, send, status, retry, or cancel operations.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `get_status` (~92 tokens)

Get fax status

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

Input parameters:

- `sendIntentId` (string): PromptFax send intent identifier returned by get_quote or session status. Use this for checkout, send, status, retry, or cancel operations.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `retry_failed_fax` (~89 tokens)

Retry failed fax

Use this after a retry-eligible failed fax to prepare a new authorization attempt.

Input parameters:

- `sendIntentId` (string): PromptFax send intent identifier returned by get_quote or session status. Use this for checkout, send, status, retry, or cancel operations.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

### `cancel` (~83 tokens)

Cancel fax send

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

Input parameters:

- `sendIntentId` (string): PromptFax send intent identifier returned by get_quote or session status. Use this for checkout, send, status, retry, or cancel operations.
- `sessionId` (string): PromptFax MCP session identifier returned by start_session. Use this to continue a session-backed fax workflow.

## Diagnostics

Captured diagnostic sections: TLS, DNSSEC, Authorisation, Transports. The full working is on the page: https://verifymcp.io/servers/app-promptfax-promptfax/promptfax#diagnostics

## Score history

- 2026-08-03: 78
- 2026-08-02: 77
- 2026-08-01: 77
- 2026-07-31: 34
- 2026-07-30: 71
- 2026-07-29: 71
- 2026-07-28: 70
- 2026-07-27: 60
- 2026-07-26: 69

## Links

- Remote endpoint: https://promptfax.app/mcp
- Changelog RSS feed: https://verifymcp.io/servers/app-promptfax-promptfax/promptfax/changelog.xml
- Changelog JSON feed: https://verifymcp.io/servers/app-promptfax-promptfax/promptfax/changelog.json
- HTML version of this page: https://verifymcp.io/servers/app-promptfax-promptfax/promptfax