# PromptFax Full Context

PromptFax is a pay-per-use web app and remote MCP connector for preparing and sending one-off outbound faxes. It is designed for users who need to upload or assemble a document, enter a destination fax number, review a quote, authorize payment, and track delivery without creating a PromptFax account or subscription.

Canonical site: https://promptfax.app/
MCP endpoint: https://promptfax.app/mcp
MCP transport: streamable HTTP
MCP authentication: OAuth for real workflow calls

## Core Public Pages

- Homepage: https://promptfax.app/
- Pricing: https://promptfax.app/pricing
- Machine-readable pricing: https://promptfax.app/pricing.json
- FAQ: https://promptfax.app/faq
- Machine-readable FAQ: https://promptfax.app/faq.json
- MCP setup: https://promptfax.app/mcp-setup
- MCP tools: https://promptfax.app/mcp-tools
- MCP tools JSON: https://promptfax.app/mcp-tools.json
- MCP submission manifest: https://promptfax.app/mcp-manifest.json
- Official MCP registry metadata: https://promptfax.app/server.json
- No-send MCP demo: https://promptfax.app/mcp-demo
- Privacy: https://promptfax.app/privacy
- Terms: https://promptfax.app/terms

## Pricing and Limits

PromptFax pricing is $2 for the first 5 pages plus 10 cents per page after that, capped at $4.50 for up to 35 pages. The user is charged only after successful delivery.

PromptFax currently supports outbound faxing to United States numbers. It accepts PDF, JPG, JPEG, and PNG uploads and supports up to 35 total pages per fax. Each destination is a separate fax workflow and requires its own quote and payment authorization.

## FAQ Highlights

PromptFax is outbound-only and does not currently provide inbound receiving fax numbers.

PromptFax does not require a PromptFax account, signup, trial, or subscription.

PromptFax can preserve the current assembled document for another send while the local browser session remains available, but each destination requires a separate payment authorization.

PromptFax stores uploaded working documents privately and treats server-side working files as short-lived. Browser-local editable pages and delivery report artifacts can remain on the user's device for up to 24 hours after last activity unless cleared sooner.

PromptFax does not claim HIPAA compliance and does not provide a Business Associate Agreement.

## MCP Setup Guidance

Use `https://promptfax.app/mcp` as the remote MCP server URL.

ChatGPT: create a custom MCP connector from ChatGPT app settings, use OAuth, and start a fresh chat after authorization. PromptFax exposes a ChatGPT widget that can use "Choose PDF from ChatGPT" when ChatGPT exposes file APIs. The widget can also accept direct upload.

Claude: add PromptFax as a custom connector from Claude's connector settings. PromptFax exposes a Claude MCP App resource for inline upload, destination, quote, payment handoff, and status polling. Stripe Checkout still opens externally. If the inline app is unavailable, use the hosted PromptFax session page fallback.

Other MCP clients: connect to the streamable HTTP endpoint, allow public discovery, authorize before real workflow calls, and use the hosted session page fallback when the client cannot pass files directly.

## MCP Tools

Tool discovery is public for directory and client probes. Real workflow tool calls require OAuth.

- `start_session`: create or resume a PromptFax MCP session. Interactive, non-destructive write.
- `attach_document`: bind a PromptFax document or HTTPS PDF URLs to a session. Non-destructive write.
- `get_quote`: create a fax quote from a session, document, or HTTPS PDF URL. Non-destructive write.
- `checkout`: start external Stripe Checkout after quote acceptance. Non-destructive write.
- `send_fax`: queue a paid fax for transmission. Destructive write.
- `get_status`: fetch workflow, payment, and transmission status. Read-only and idempotent.
- `retry_failed_fax`: prepare a retry flow after a retry-eligible failed fax. Non-destructive write.
- `cancel`: cancel an active send when cancellation is still possible. Destructive write.

## Safety and Payment Notes

The user reviews a quote before payment. Stripe Checkout handles payment authorization externally. PromptFax uses webhook-confirmed payment authorization as the source of truth; a browser redirect alone is not proof that a fax is authorized to send.

PromptFax queues a real fax only after explicit user intent and confirmed payment authorization. Delivery status and delivery reports are available through the web app, ChatGPT widget, Claude MCP App, and status polling where supported.

## Machine-readable Metadata

- MCP manifest: https://promptfax.app/mcp-manifest.json
- MCP tools JSON: https://promptfax.app/mcp-tools.json
- MCP registry server.json: https://promptfax.app/server.json
- Square PNG logo 512: https://promptfax.app/brand/promptfax-logo-512.png
- Square PNG logo 1024: https://promptfax.app/brand/promptfax-logo-1024.png
- Square SVG logo: https://promptfax.app/brand/promptfax-logo.svg
- OG image: https://promptfax.app/brand/promptfax-og.png