PayPerFax

What PayPerFax MCP server does

The PayPerFax MCP server lets an AI assistant prepare a fax without handling payment directly. The assistant can provide a destination fax number, an email address, and either a Markdown letter it generated or a notice that the user still needs to attach a file. The service returns a link where the user can review the fax, see its price, add a file when needed, and pay in a browser.

No account, subscription, or API key is required. The hosted endpoint is available at https://fax.payperfax.com/mcp.

How it works

The connection uses Streamable HTTP and does not require authentication. After the assistant calls create_fax, the user opens the returned link and completes the review and payment flow. Nothing is sent or charged before payment. A person—not the assistant—authorizes and pays for each fax.

For generated correspondence, Markdown text supplied by the assistant becomes the fax document. MCP does not transfer files from a chat application to the server, so users with signed forms, scans, or PDFs add those files in the browser after opening the pre-filled link. Coding agents with shell access can also send a file over HTTP using the separate PayPerFax API, but that API is outside the MCP tool set described here.

Setup and configuration

Add a custom MCP server in a compatible client’s connector or integration settings. Use PayPerFax as the name and https://fax.payperfax.com/mcp as the URL, then enable the connection. The assistant should be told the user’s country so the displayed price can use the appropriate currency.

Gemini CLI can install the repository extension with:

gemini extensions install https://github.com/payperfax/fax-mcp --ref main

The extension connects to the hosted service; it does not run the server locally. Use /mcp in Gemini CLI to inspect the connection and available tools.

Tools and capabilities

The PayPerFax MCP server exposes three tools:

• create_fax prepares a fax and returns a payment and review link. Inputs include the fax number, email address, and either Markdown content or an indication that a file is required.
• get_fax_status reports whether a fax is queued, sending, delivered, or failed.
• list_supported_formats returns accepted input types, size limits, and supported languages.

The preview, payment page, and email communications can be presented in English, Spanish, German, French, Japanese, or Korean.

Limitations and notes

The hosted server implementation is not included in the public repository, which documents the service and its registry entry. The repository files are MIT-licensed, but that license does not apply to the hosted implementation.

Users should verify destination numbers independently before sending, especially for sensitive documents. The assistant may identify a number from an external source, but the material specifically recommends checking an IRS number against irs.gov before faxing tax documents. Payment must happen in a browser for every fax, and a file already present in a chat app is not automatically transferred through MCP.