Metis Check

com.metisfoundry.check-apiPublished by check-api.metisfoundry.comOfficial publisherv1.0.0Updated Nov 6, 2026

Checks an answer's citations at the registries that issue them. Every check files a signed report.

VerifiedStreamable HTTPWeb executableWeb Search & ScrapingKnowledge & MemorySecurity & Monitoring

Overview

AI-generated overview

Checks whether identifiers cited in an AI answer actually exist, by querying the registries that issue them, and returns a signed report.

What you can do
  • Check cited identifiers against the registries that issue them (DOI, PubMed, arXiv, ORCID, ROR, ISBN, LEI, ISIN, CUSIP, SEC CIK, EIN, NPI, UK company numbers, domains and more)
  • Get each identifier back in one of four states: settled true, settled false, not decidable or unreachable, plus a not-checked list with reasons
  • Receive a signed report with its own id, a PDF, the registry query and the SHA-256 of each registry answer
  • Share a report link that anyone can open and recheck live against the registries
When to use it
Useful when an assistant produces answers with citations and you need to confirm the cited identifiers are real and registered before relying on, publishing or forwarding them. It verifies registration, not whether a source actually supports a claim.
Requirements
Remote MCP endpoint over streamable HTTP with OAuth sign-in; a free Metis account is created on first connection. No local runtime, packages or environment variables. A paid plan is needed beyond the free monthly check allowance.
Before you install
OAuth sign-in creates an account tied to the service; free tier is limited to 5 checks a month and Pro or Team plans cost money. Reports are shareable by link, so anyone with the link can view them. Only identifiers, positions and a hash are stored, not passages, but the identifiers you submit go to third-party registries.

Installation

In SourceWeft

  1. Open Metis Check in the dashboard and add it to a workspace.
  2. Connect the required credentials. They are stored privately and never shown on public pages.
  3. Enable the server for the chats that should use its tools.

Web executable via Streamable HTTP. Remote servers run from the web runtime once configured in a workspace.

Use with an agent

Paste this prompt into Claude Code, Codex, Cursor or another agent — or into SourceWeft chat. The agent reads this server's install guide, shows you its publisher, endpoint and sign-in, and adds it to your client once you agree. Keys never go into a command.

Read https://sourceweft.com/mcp/com.metisfoundry.check-api%2Fmetis-check/install.md and connect the MCP server it describes to my client. Before changing any config, show me its publisher, endpoint and sign-in method and wait for my OK. Never put an API key in a command or in a file I would commit; ask me where it should come from.

Read the install guide the agent follows

Other MCP clients

Add this to your client's mcpServers config. The client completes OAuth sign-in on first connect.

{
  "mcpServers": {
    "metis-check": {
      "type": "http",
      "url": "https://check-api.metisfoundry.com/mcp/check"
    }
  }
}

README

Metis Check

The check every cited AI answer needs before you rely on it. A citation that looks complete and points to nothing costs a correction, a retraction or a sanction. Metis Check asks the registries that issue each identifier whether it exists and what it says. DOI, PubMed, arXiv, ORCID, ROR, ISBN, LEI, ISIN, CUSIP, SEC CIK, EIN, NPI, UK company numbers, domains and more. Each identifier comes back in exactly one of four states: settled true, settled false, not decidable (a person decides) or unreachable (a delay, not evidence). Every check ends in a signed report with its own id, a PDF and a recheck button anyone can press.

By Metis Foundry. One account covers ChatGPT, Codex, Claude, Claude Code, Cursor and VS Code. Every account starts with 5 checks a month; plans.

[A Metis Check report]

A real report: three identifiers settled true, one settled false. Open it and press Recheck.

Install

ClientHow
Claude (web, desktop, mobile)Settings → Connectors → add a connector by URL: https://mcp.metisfoundry.com/mcp. Once Metis Check is listed in the connectors directory, choose it there.
Claude Code/plugin marketplace add MetisFoundry/metis-plugins then /plugin install metis-check@metis, or claude mcp add --transport http metis-check https://mcp.metisfoundry.com/mcp
Codex CLIcodex plugin marketplace add MetisFoundry/metis-plugins then codex plugin add metis-check@metis
ChatGPTThe Metis Check plugin is submitted to the OpenAI directory. Until it is listed: Settings → Connectors → add by address https://check-api.metisfoundry.com/mcp/check
CursorAdd to Cursor
VS CodeAdd to VS Code (web redirect), or code --add-mcp '{"name": "metis-check", "type": "http", "url": "https://check-api.metisfoundry.com/mcp/check"}'
Any MCP clientRemote server https://check-api.metisfoundry.com/mcp/check (OAuth sign-in; a free account is created on first connection). Registry name com.metisfoundry/metis-check.

Sign in or create a free Metis account when the client asks.

Try it in one click

The prompt asks Metis Check to check four references, one of them invented. The invented one comes back settled false, with the registry that said so.

What you get

  • Four states, nothing hidden: settled true, settled false, not decidable, unreachable, and a not-checked list with the reason for each.
  • A report that rechecks without Metis: every line carries the registry query and the SHA-256 of the registry's answer; signed JSON and a PDF.
  • Shareable: anyone with the link can open the report and press Recheck; the registries are asked again, live.
  • Private: passages are never stored, only the identifiers, their positions and a hash. Metis never asks for conversation history.
  • Honest scope: Metis Check establishes that an identifier is registered and what the registry says. It does not decide whether a paper supports a claim.

Plans

Free: 5 checks a month. Pro: $29 a month (or $276 a year), 2,000 checks, case law included. Team: $249 a month (or $2,388 a year), 15,000 checks, 5 seats. Checks that cannot be settled cost nothing. Details: https://check-api.metisfoundry.com/check/plans

Repository layout

  • .agents/plugins/marketplace.json — Codex marketplace (metis); plugin in plugins/metis-check
  • .claude-plugin/marketplace.json — Claude Code marketplace (metis); plugin manifest in plugins/metis-check/.claude-plugin
  • plugins/metis-check/.codex-plugin/plugin.json — Codex plugin manifest (icon assets/icon-codex.png)
  • server.json — official MCP Registry manifest
  • PUBLISH.md — how the listings are published

Support and license

[email protected]. Proprietary: the files in this repository are not open source. You may install and use them, unmodified, with the Metis Check service, and plugin directories may mirror the unmodified plugin bundle so users can install it (LICENSE, NOTICE.md).

Source: README.md at commit 914fe72

Tools

0
This server asks you to sign in, so SourceWeft could not read its tools without an account and has not indexed them. What a connected account sees can depend on that account and its permissions.

Version history

1
  1. v1.0.0LatestOct 29, 2026

Score

75% of the applicable checks met

How complete this listing is, computed from the registry entry, the endpoint and public sources. Not a rating of the server and not a statement that it is safe or working today: reachability is a dated check, and no installs or reviews go into the score.

  • Reached in the last 30 daysRequired25 pts
  • Auth declaredRequired10 pts
  • Tools listed15 pts

    Answer tools/list without a credential, or ship a package that starts in a sandbox without one.

  • DescriptionRequired15 pts
  • Logo10 pts
  • Documentation15 pts
  • License10 pts

    Declare a license in the repository or the registry entry.