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FactStamp MCP Server

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FactStamp is answering right now. Last checked 13 min ago. It exposes 18 tools. Last commit 28 Oct 2026.

Verify a company, figure or citation before you rely on it. Card or crypto; signed receipt.

Uptime history 34 days of history · worst day 98%
34 days agonow
100.0%
Uptime 24h
182 of 182 checks
18
Tools
read from the server
988 ms
Response time
average over 24h
0
Stars
last commit 28 Oct 2026

What changed 39

Every tool that appeared, vanished or quietly changed what it asks for. Recorded since 29 September 2026. No other catalogue keeps this.

28 Oct a tool changed version2 times that day
28 Oct a tool appeared audit_claims
21 Oct 5 tool descriptions were rewritten buy_card_package, check_document, list_card_packages and 2 more
20 Oct 2 tools appeared check_entity_file_ca, check_entity_file_il
16 Oct a tool description was rewritten list_card_packages
15 Oct 7 tool descriptions were rewritten8 times that day check_document, check_entity_file, check_figure and 4 more
15 Oct 2 tools appeared buy_card_package, list_card_packages
13 Oct a tool description was rewritten check_entity_file
11 Oct a tool description was rewritten check_entity_file
9 Oct a tool appeared check_entity_file
and 17 more, back to 29 September 2026

Nothing serious here today

Today is the operative word: we check FactStamp every 15 minutes and re-read its code on every release. Watch it and you find out the day that stops being true.

Three servers free · no card

Connect this server

Endpoint below is the one we actually reach during checks — not the one copied from a README. Last verified 13 min ago.

run in your terminal
claude mcp add factstamp --transport http https://factstamp.agentrails.workers.dev/mcp
Settings → Connectors → Add custom connector, then paste this address
https://factstamp.agentrails.workers.dev/mcp
~/.codex/config.toml
[mcp_servers.factstamp]
url = "https://factstamp.agentrails.workers.dev/mcp"
.cursor/mcp.json
{
  "mcpServers": {
    "factstamp": {
      "url": "https://factstamp.agentrails.workers.dev/mcp"
    }
  }
}
.vscode/mcp.json
{
  "servers": {
    "factstamp": {
      "type": "http",
      "url": "https://factstamp.agentrails.workers.dev/mcp"
    }
  }
}

This server publishes 1 more address. The block above uses the one we reach during checks; the full list is under Endpoints below, and the author may intend a particular one for your client.

Available tools 18

Read directly from the server with tools/list, grouped by what they act on. If a tool disappears, we record the date.

entity
check_entity
Verify a legal entity: does this company exist, under which identifier and jurisdiction, and is its registration current? Cited to open primary registers (the GLEIF LEI index and US SEC EDGAR). Returns found, ambiguous, not_found or unknown; a near name match is never reported as a match. Not advice, not a credit check, not a sanction screen. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
check_entity_file
The entity file: ONE paid answer holding everything we hold about one company: the whole picture in ONE call rather than four separate facts stitched together, at the point of signing, onboarding, paying or acquiring a counterparty. It holds identity and standing, the registered office, SIC activity and previous names, the filing position, a sanctions screen across our six lists, and the ownership the registers publish (the persons with significant control where a register publishes them, and the declared parent relationships where a company has an LEI, with beneficial ownership stated as not public in nearly every country we cover) — each cited to the register it came from with its retrieval time — plus ONE coverage block naming every register consulted and every one NOT consulted. Returns found, ambiguous, not_found or unknown for the company itself; a register that was not read is named as not read, never guessed. 33p UK-facing, settled in USDC at the dated rate. Not advice, not a credit check. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
check_entity_file_ca
Canadian company lookup and Canadian federal corporation register check by nine-digit Business Number (BN) only: corporation number, BN, governing legislation, every registered name with type, current flag and effective date, the register's own status, the registered address, the MINIMUM and MAXIMUM NUMBER of directors as a count rather than the people, and the annual-return history with dated incorporation and other activities, in six sections from one live read of Corporations Canada, with one signed receipt and one coverage block. The public endpoint is keyed by Business Number, so a name alone cannot reach it; provincial and territorial corporations are a different register this file does not read; director and officer names and beneficial owners are not published on this path. Returns found, not_found or unknown; unknown is a first-class answer and is not charged. Not advice, not a credit check and not a KYB service. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
check_entity_file_il
Israeli company lookup and company register check by company number (nine digits, with its own check digit) or by registered name, Hebrew or English: identity, corporation type, the register's own status and sub-status, description and stated purpose, incorporation date, government-company flag and restrictions, last annual-report year and the structured registered address, in seven sections from one live read of the Registrar of Companies dataset on data.gov.il, with one signed receipt and one coverage block. No officers, directors, shareholders or beneficial owners as people, and no financial statements: those sit behind the Registrar's paid company extract, which this file does not read. Amended returns and a change registered after the dataset's last refresh may not yet appear. Returns found, ambiguous, not_found or unknown; unknown is a first-class answer and is not charged. Not advice, not a credit check and not a KYB service. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
verify
verify_bulk
Check a whole list in one call: a bibliography or a dependency manifest. Send items[] of {tool, input} or the citations[]/packages[] shorthand. Up to 12 items at a flat US$0.12 on this door; longer lists pay 0.016667 an item on the pack-funded HTTP door (POST /bulk, up to 25 items). Every item is answered by the same door that answers a single call, so the verdicts cannot disagree. This door takes a LIST of references or package versions, not prose: to check the claims inside a document, use check_document, and to check one reference use verify_citation or verify_package. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
verify_citation
Says whether a citation can be repeated. Submit a DOI, an arXiv ID or a paper title: returns whether it exists, what it is (title, authors, year, container) and whether it has been retracted, cited to Crossref and arXiv. Optionally send what your document claims (title, authors, year, journal) and every field is compared one by one — a disagreement is reported as mismatch, never as verified. A near title match is never reported as verified; a title that is absent from both returns not_found. Not advice. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
verify_package
Reports on a dependency at the point of installation. Submit a package and version plus its ecosystem: returns whether that exact version exists, whether it is yanked or deprecated, and every advisory OSV lists against it. An invented version returns not_found with the real versions nearest to it, and an invented name returns the published names that look like it — which is the point, because that is how slopsquatting gets installed. Not a security audit. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
watch
watch_add
Watch ONE citation or ONE package version instead of checking it once. Send kind ('citation' or 'package') and the subject (a DOI, an arXiv ID or a title; or npm:[email protected]). The first check is answered immediately and signed, then re-checked daily for 30 days; every real change (a retraction, a new advisory, a yanked version) is recorded with its own signed receipt. Returns a read URL and a token shown once; optionally send an https webhook and each change is POSTed to it. For a whole list of references under one purchase use watch_portfolio; for a one-off answer that does not need watching, use verify_citation or verify_package. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
watch_portfolio
Watch a whole list instead of one reference at a time: up to 25 citations or package versions re-checked every day for 30 days under one token. US$5 a portfolio — 20 cents a reference, under a cent a check — and the first check on every reference is answered and signed immediately. Each real change carries its own signed receipt, and nothing is sent when nothing changed. ONE purchase covers the whole list: for a single subject on its own, use watch_add. Returns a read URL and a token shown once. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
audit
audit_claims
Audit what an agent believes about companies. Send up to 10 claims ({subject:{identifier|name|jurisdiction}, field, value}) and get, claim by claim: supported (the register says this), contradicted (it says something else, shown), stale (the register records it as FORMER, with the date it changed) or not_checkable (we could not check it, and why). Every verdict carries the register's own date and a citation, and the whole batch gets ONE receipt. field is a name from the published vocabulary (legal_name, previous_name, identifier, status, legal_form, registration_date, dissolution_date, registered_address, activity_code), never open text: a field outside it is not_checkable, not a guess. US$0.20 on this rail for up to 10 claims; longer audits go to POST /audit, which prices the body at US$0.02 a claim with a US$0.20 floor. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
buy
buy_card_package
Included. Opens a Stripe Checkout Session for one card package and returns its payment link and its session id. This tool charges nothing and produces no artefact: on the card rail the thing that taps is a human. The package's work runs only at its redeem path, after Stripe's own record says that session is paid.
card
list_card_packages
Included. The one-off card packages as one machine-readable catalogue: the 11 products and their 13 prices in Australian dollars, the unit one payment buys for each SKU, what the package returns, and where the input is sent. One payment each, nothing metered, nothing subscribed. The per-call doors stay open beside them.
document
check_document
A whole document in one call: the claims that can be verified against a primary source, each answered by the door that owns it with its own signed receipt, plus one receipt over the document. Extraction is mechanical, so the claim list and the count are reproducible from your document alone — nothing is inferred. This rail answers the first 5 claims for a flat US$0.25 (5 cents a claim); a better-funded document goes to the pack-funded HTTP door (POST /document, up to 25 claims at the same 5 cents a claim), whose included preview lists the claims and the price before anything is charged — use it first if you are unsure the document holds anything checkable. This door reads PROSE: to check a bare list of references or package versions, use verify_bulk, and a single claim belongs to check_figure, check_entity, verify_citation or verify_package. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
figure
check_figure
Submit the dated figure you are about to act on. Returns verified, stale, contradicted or unknown, cited to the publisher's own series with its as-of date. Relevant wherever a number is going onto a page, deck or decision. Not advice. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
route
route_claim
Included. Shows which series a claim would be routed to, the value and date extracted, and the signals behind the score. Returns NO verdict — pay for check_figure when you want one.
sanctions
check_sanctions
Sanctions screening of a name, for whether a person or company is on a sanctions list — and which one. Reads OFAC SDN, the UN consolidated list, the EU Financial Sanctions File and the UK Sanctions List, and returns listed, mismatch, not_found or unknown. The answer names the lists that were consulted with each one's retrieval date (and the UK list's own report date); a list that was not consulted is named as not consulted, and unknown is the answer when we cannot tell. A near name is never reported as the same party, and a listed verdict stands even when another list was not consulted. Not advice, not a legal determination. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.
series
list_series
Included. What this engine covers, the publisher and as-of date behind each series, and the no-guess rule.
vat
check_vat
An EU VAT number check — VAT validity, and the VAT registration behind it. Reads the official VIES service (European Commission), keyless. Returns valid, invalid or unknown — an outage is NEVER reported as invalid — with the member state, the register's own request date, and the trader identity only where that member state discloses it. Some member states disclose nothing; the answer says so rather than showing an empty string. GB is out of scope after Brexit (XI, Northern Ireland, is covered). Not tax advice, not a credit check. Comes with an Ed25519-signed receipt covering the question, the verdict, the sources and the time, checkable offline against the published key at /.well-known/factstamp-issuer.json — so the check itself can be audited later by someone who was not here.

Endpoints

URLTransportStateLatencyChecked
https://factstamp.agentrails.workers.dev/mcp streamable-http answering 1048 ms 13 min ago
https://agents.factstamp.dev/mcp streamable-http answering 961 ms 13 min ago

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FactStamp — questions

Answers built from our own checks of this server.

What can FactStamp do?
It exposes 18 tools, read directly from the server on our last check. Among them: audit_claims, buy_card_package, check_document, check_entity, check_entity_file, check_entity_file_ca and 12 more. The full list with descriptions is on this page — we take it from the server itself via tools/list, not from a README. How MCP servers expose tools in the first place →
What is FactStamp mostly used for?
Its tools cluster around entity, verify and watch. That is what this server is built to work with — the grouping comes from the actual tool names, not from a category we assigned.
Is FactStamp working right now?
We send a real MCP handshake every 15 minutes. Over the last 24 hours 182 of 182 checks got a reply (100.0%), average response time 988 ms. The bar chart above shows every period we have measured.
How do I connect FactStamp?
Copy the ready config from this page. We generate it for Claude Code, Claude Desktop, Codex, Cursor and VS Code, each in the form that client actually reads. It is a remote server, so there is nothing to install — the client connects to the address.
Does FactStamp need an API key?
No. FactStamp completed a full MCP handshake with us as an anonymous client and listed its tools without asking for anything. All 18 of them are readable on this page. This is what we observed, not what the docs claim.
How fast is FactStamp?
It answers our handshake in 988 ms on average, which is faster than 5% of all working MCP servers we measure. That is on the slow side — worth knowing if the tool sits inside an interactive loop. The comparison comes from our own checks across the whole registry, every 15 minutes.
Is FactStamp open source?
We cannot say either way: 0 stars on GitHub, but we could not determine the licence, and without one the code is not open source by default.