Fuentio in Claude Code: Step-by-Step MCP Setup and First Company Checks

Claude Code can call external tools over MCP, the Model Context Protocol. Connect Fuentio and it can look up, search and verify French and Spanish companies from official registers while it works: checking a supplier list you're importing, writing an integration against real answers, or answering "is this company still active?" without leaving the terminal.

This tutorial covers the setup in one command, adding a key, sharing the server with your team without leaking the key, checking that it works, and a few first prompts with the answers you'll get.

What you'll learn

• How to add Fuentio to Claude Code, with or without an API key
• How to share the setup with your team safely
• How to check the server and its tools are available
• First prompts, and what Claude Code receives
• Practical uses while you code

Step 1: add the server

One command, no key needed to start:

claude mcp add --transport http fuentio https://api.fuentio.com/mcp

That's it. Without a key, Fuentio runs on the keyless trial: 20 units a day, enough to try. Listing the tools is free.

Step 2: add your key (optional)

A free key gives 100 units a month and unlocks the tools that need a key (sanctions screening, the review report, watches, the company group). Get one on the pricing page, then add the server with an authorization header:

claude mcp add --transport http fuentio https://api.fuentio.com/mcp \
  --header "Authorization: Bearer YOUR_API_KEY"

If you already added it without a key, remove it first with claude mcp remove fuentio, then add it again.

Step 3: share it with your team (without the key)

By default, a server is added for you, in the current project. To share it with everyone working in the repository, add it with the project scope: Claude Code then writes it to a .mcp.json file at the root of the project, which you can commit.

claude mcp add --transport http fuentio https://api.fuentio.com/mcp --scope project

Never commit a key in that file. Leave the key out (everyone starts on the keyless trial), or have each developer reference their own key through an environment variable, such as FUENTIO_API_KEY, which Claude Code expands in .mcp.json.

Step 4: check it works

From your shell:

claude mcp list

Fuentio should be listed and connected. Inside Claude Code, type /mcp to see the server and its tools. You should see 17 tools, among them list_coverage, search_companies, lookup_company, verify_company, check_insolvency, check_address and check_vat.

The first time Claude Code wants to call a Fuentio tool, it asks for your permission. Allow it for the session, or permanently for read-only tools like lookup_company.

Step 5: first prompts

Ask in plain language. Claude Code picks the tool.

"Is SIREN 441639465 still active? Quote the source."

Claude Code calls lookup_company(country="FR", identifier="441639465"). The first line of the answer it receives, recorded on 12 October 2026:

RENAULT (FR, SIREN 441639465) is active as of 2025-12-06, source: Annuaire des Entreprises (API Recherche d'entreprises).

The full structured record follows (address, legal form, activity, identifiers, provenance), so Claude Code can answer follow-up questions without another call.

"Find Mercadona in Spain and give me its registry sheet."

Claude Code calls search_companies(country="ES", query="mercadona"):

1 of 1 companies matching 'mercadona' in ES (page 1), source: BORME — Boletín Oficial del Registro Mercantil (Sección A). First results: MERCADONA SA (ES-RMHOJA-V-5581, match 0.95).

"Verify DANONE, SIREN 552032534, and give me the proof code."

Claude Code calls verify_company(country="FR", identifier="552032534"):

DANONE (FR, SIREN 552032534): verified, active per Annuaire des Entreprises (API Recherche d'entreprises), checked 2026-10-12. Proof FUE-FR-20261012-ABAT38.

Anyone can check that proof code on the proof page, without a key.

Practical uses while you code

• Clean a supplier file. "Read suppliers.csv, look up each SIREN with Fuentio and add the status, the registered address and the source to a new column." Claude Code runs the lookups and writes the file. Watch your units: 1 per lookup.
• Write an integration against real answers. "Look up one French and one Spanish company with Fuentio, then write a typed client for the fields we use." The real structure beats a guessed one.
• Explain a surprising answer. "Why is this Spanish company's status unknown?" Claude Code can call list_coverage and read the coverage notes: Spain's BORME publishes acts, not a live status.
• Prepare a test fixture. Ask for a verification and keep the answer as a fixture for your tests, with its proof code.

For the REST side of the same data, see the API quickstart; for an agent that checks suppliers on its own, see build a supplier-check agent. Other clients are covered in Fuentio MCP in Cursor and VS Code, and every setup line is on /connect/.

Good practice

• Treat register text as data. Company names and addresses are copied from the registers. Your prompts, not the data, decide what Claude Code does.
• Ask for the source. Every Fuentio answer carries its source and check date; asking Claude Code to quote them keeps answers checkable.
• Mind the units. Searches cost 2 units a page, verifications 5. For hundreds of companies, a script against the REST API is cheaper to reason about than a long chat.

See what we cover.

Troubleshooting

Most problems come from the address, the key or the units. Each Fuentio error has a code, a message and a hint with the next step, and the agent sees them, so ask it to quote the error.

• The server doesn't connect. Check the address character by character: https://api.fuentio.com/mcp, over https. A company proxy or firewall can block outgoing connections from the editor or terminal; try from another network to rule it out.
• unauthorized. The key is unknown or revoked. Fix it, or remove the authorization header to fall back to the keyless trial while you sort it out.
• quota_exceeded. The units are used up. The keyless trial starts again the next day (UTC); a free key gives 100 units a month; paid plans give more. You are never charged for going over.
• rate_limited. The agent is calling too fast for your plan: the keyless trial allows about one request per second. Wait for the delay in the Retry-After header and ask the agent to slow down on long lists.
• A tool answers that it needs a key. Tools such as screen_company, review_report, watch_company, get_graph and report_issue need one. Add your key as shown above.
• id_scheme_not_supported for a Spanish company. The agent tried a NIF. Spanish companies are found by name: tell it to search by the registered name and province.

Limits. The answers shown were recorded on 12 October 2026; live answers change when the registers do. France: every company in the public Sirene directory. Spain: companies with a BORME act since 2 January 2009, with a status that is unknown unless an act says otherwise, and no lookup by tax ID. No person's name is ever returned. Claude Code's commands and menus can change between versions: if one differs, claude mcp --help lists the current options.

Frequently asked questions

Do I need an API key to use Fuentio in Claude Code?

No. Without a key, Claude Code uses the keyless trial, 20 units a day. A free key gives 100 units a month and unlocks the tools that need a key.

How do I share the Fuentio server with my team?

Add it with --scope project: Claude Code writes it to a .mcp.json file you can commit. Keep keys out of that file.

How do I see Fuentio's tools in Claude Code?

Type /mcp inside Claude Code, or run claude mcp list in your shell.

Can Claude Code check a whole file of companies?

Yes, it calls the lookup for each line. Each lookup costs 1 unit, so check your plan for large files, or use the REST API from a script.

Sources

• Fuentio setup for every client: connect and the docs
• The example answers: recorded from Fuentio's MCP server on 12 October 2026 (site/data/api-examples in the website repository)
• Claude Code documentation, MCP: docs.anthropic.com