FACTRAIL

Evidence infrastructure for AI agents.

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What it can do

  • Factrail Capabilities: Discover available capabilities, inputs, fields, sources, versions, and limitations. Call first to inspect current coverage and source state.
  • Factrail Assess: Assess a structured real-world situation and return an EvidenceEnvelope. Currently supports beta import assessments; results expose source coverage and support levels.
  • Factrail Verify: Verify structured facts for a supported subject. Currently supports French companies by SIREN or SIRET; returns Evidence with provenance, freshness, coverage, conflicts, and a receipt

What data it sees

Do you need an account

No: the server works without sign-in

Evidence infrastructure for AI agents.

FACTRAIL gives agents structured, source-backed real-world evidence with provenance, freshness, support levels, coverage, conflicts, and reusable receipts. Call factrail_capabilities to discover actual support, then use factrail_verify, factrail_assess, and factrail_get_receipt.

The strongest current capability verifies French company facts using INSEE / Sirene and BODACC. Trade/import assessment is Beta and may be partial or provisional. Official TARIC snapshot ingestion is supported, but no genuine Commission snapshot is installed. Access2Markets is secondary; curated tariff/VAT references remain provisional. Receipts are integrity-checked content-addressed records, not signatures or blockchain attestations.

How to connect

How to connect FACTRAIL to Claude

The server address to paste into Claude settings:

https://factrail--baronsigma.run.tools

  1. Open Claude (claude.ai or the desktop app).
  2. Go to Settings → Connectors.
  3. Click Add custom connector.
  4. Paste the server address copied below into Remote MCP server URL and click Add.
  5. In a chat, click + → Connectors and switch the new connector on.

Custom connectors are available on Free, Pro, Max, Team and Enterprise plans (Free is limited to one). On Team and Enterprise an organization Owner adds the connector first under Organization settings → Connectors.

Authorization

After you click Add, a sign-in window for the service opens. Sign in with your own account and approve access. Claude never sees your password.

How to connect FACTRAIL to ChatGPT

The server address to paste into ChatGPT settings:

https://factrail--baronsigma.run.tools

  1. Open ChatGPT in a browser (chatgpt.com). A Plus, Pro, Business, Enterprise or Edu plan is required.
  2. Turn on developer mode once: Settings → Apps → Advanced settings → Developer mode.
  3. Open Settings → Connectors and click Create.
  4. Fill in the form: Name (anything), Description (one line about what the service does), MCP server URL (copy it below).
  5. Under Authentication choose OAuth if the service requires sign-in, otherwise None. Click Create.
  6. In a new chat open + → Apps/Connectors and enable the connector.

OpenAI has renamed this section before (Connectors → Apps/Plugins). If the label differs, search settings for "developer mode". On Business/Enterprise workspaces an admin must allow custom connectors first.

Authorization

On first use ChatGPT opens the service's sign-in window. Sign in and approve access.

How to connect FACTRAIL to Cursor

The server address to paste into Cursor settings:

https://factrail--baronsigma.run.tools

Fastest: click Open in Cursor below and confirm the prompt.

Manually:

  1. In Cursor open Settings → Cursor Settings → MCP and click Add new global MCP server.
  2. Paste the JSON copied below into ~/.cursor/mcp.json (per project: .cursor/mcp.json in the repo root).
  3. Save the file. The server appears in the MCP list; authorize it there if asked.

Authorization

If the service needs sign-in, an authorize button appears next to the server in the MCP list.

Server tool list (7)

Raw names from tools/list. Only developers need these.

factrail_capabilitiesDiscover available capabilities, inputs, fields, sources, versions, and limitations. Call first to inspect current coverage and source state.
factrail_assessAssess a structured real-world situation and return an EvidenceEnvelope. Currently supports beta import assessments; results expose source coverage and support levels.
factrail_verifyVerify structured facts for a supported subject. Currently supports French companies by SIREN or SIRET; returns Evidence with provenance, freshness, coverage, conflicts, and a receipt.
factrail_get_receiptRetrieve a stored EvidenceEnvelope by receipt ID. Recomputes its content hash and rejects altered content; this checks integrity, not truth.
verify_french_companyCompatibility tool for French company lookup by SIREN/SIRET. New integrations should prefer factrail_verify for an EvidenceEnvelope.
assess_importCompatibility tool for beta EU import assessment. Coverage may be partial or provisional; this is not a binding customs result. New integrations should prefer factrail_assess.
analyze_companyDeprecated experimental compatibility-only tool. Financial and credit data sources are unavailable; returned fields are null. Prefer factrail_verify for supported company facts.