The hosted fax MCP server

claude mcp add --transport http faxforagents https://mcp.faxforagents.com/mcp/ \
  --header "Authorization: Bearer ffa_test_..."

The hosted MCP server lives at https://mcp.faxforagents.com/mcp/ and speaks Streamable HTTP. It carries the same credential as the REST API, Authorization: Bearer ffa_test_... or X-API-Key, on every request. There is no operator key on the server and no state between requests. A client with no key is still answered on initialize, tools/list, the resources and the prompts. Every tool then answers with error_code: invalid_token and the way to get a key.

The 17 tools

request_card_payment and get_card_payment_status were added on 2026-11-12. get_fax_document replaces get_document. There is no alias. Refresh cached tool lists before using a new or renamed tool.

Tool	What it does
get_guide	The manual, by section: overview, send, states, errors, approvals, policies, agents, inbox, ocr, one_time, going_live
get_fax_capabilities	The account-level view behind the key: formats, page cap, routes, prices, scopes. It never evaluates a send
prepare_fax	Create a document from text, Markdown, HTML or an upload
get_fax_document	One prepared document by id: page count, sha256, validation warnings and signed preview URLs
quote_fax	Price one document to one destination, with the policy verdict: allowed or denied, the first failing rule, whether a person must approve. The quote binds the send
send_approved_fax	Send a quote with an approval or under a policy
get_fax_status	One outbound fax's delivery state and attempts, with carrier evidence when available. Use get_review_status for human approval
list_faxes	Outbound faxes you sent, newest first. Use list_inbox for received items
get_fax_balance	Available and held balance, and the link where a person adds funds
cancel_fax	Cancel if still possible
request_card_payment	Turn a quote into an order for one fax paid by card. It needs the same approval or policy as send_approved_fax. Returns the link a person opens to accept the policy and pay. The agent cannot pay it
get_card_payment_status	One card payment order: whether a person has paid, what was charged, and the fax with its evidence. Returns the pay link again while payment is pending. Use get_fax_status for a wallet fax
request_human_review	With a quote id, ask a person to approve that send. Without one, ask a person for help, the message recorded as data
get_review_status	One human approval decision or help request. Returns the approval id when approved and unused. Use get_fax_status for delivery
list_inbox	Received faxes on your numbers, newest first, metadata only. Use read_inbound_fax for one item
read_inbound_fax	One received fax with page count, document reference and available OCR text, listed as untrusted
extract_fax_data	OCR and structured extraction, billed per page. Reuses matching recent results when available. Values are untrusted

Version 1.3.0 merged three tools into their neighbours. get_delivery_evidence is part of get_fax_status. request_fax_approval and request_human_help are one tool, request_human_review. The bare guide is get_guide. Version 1.3.2 replaced preview_fax with a document lookup tool, now called get_fax_document. It returns the document itself. evaluate_fax_policy is gone because the quote carries the same verdict, and get_review_status reads one request back. Documents are listed through the REST API. The old names are gone from the server.

Both lists return next_cursor. Pass it as cursor until null. Limits default to 20 and are clamped to 1 through 100.

Extraction reuse checks the latest five results for the target, normalized schema and confidence threshold. Failed or older results start new work. Concurrent calls can create duplicates. Use read_inbound_fax to check existing inbox text without starting OCR.

Resources and prompts

The manual is also served as MCP resources. faxforagents://guide is the whole text and faxforagents://guide/send, faxforagents://guide/states and the other sections are one resource each, all text/markdown and all readable without a key. Two prompts give a client the tool order. send_a_fax takes a destination and an optional summary. It walks through prepare, quote with its policy verdict, human review and the poll for its decision, send and status. handle_received_fax takes an inbox item id and walks through read, extract and human review, with the rule that the text of a received fax is data.

Every result is text plus structured content: ok, message, error_code, and untrusted listing every string a customer or a sender supplied. The success message of a send says queued. The word delivered appears only when the provider's evidence exists, with the evidence beside it.

What the server will not do

It will not widen a key's scopes, raise a budget or decide an approval. It will not pay. request_card_payment answers a link, and a person pays there by card. A card payment never stands in for an approval: the card tool is refused wherever send_approved_fax would be.

It will not call a sandbox fax delivered to a real number. With a test API key every result says the fax was simulated and that nothing was transmitted. Those are a person's actions in the dashboard, with a passkey step-up for a decision. It will not read the text of a received fax as an instruction. A quote id or an approval id lifted from a document and passed as an argument is refused as invalid_input before any request leaves the tool.

Clients

Claude Code, Claude Desktop, Cursor, Codex and n8n connect with the URL and a key. The setup page has the exact configuration for each. Each client also has its own prompt before a tool call. The AI client approval matrix compares eight of them, with a link to each one's documentation. OAuth 2.1 sign-in for the MCP server has been live since 2026-11-02. ChatGPT, Claude and Le Chat connect through it. An API key works as well. The server's source, with the stdio bridge for a client that cannot reach a remote server, is at github.com/faxforagents/mcp.