Lombardia Trains MCP

An MCP server that answers questions about Lombardy trains: departure and arrival boards, live delays, platforms, stop-by-stop progress, cancellations and crowding — and plans journeys with a change, from the regional timetable Regione Lombardia publishes as open data. It reads the public ViaggiaTreno (RFI/Trenitalia) and Trenord APIs. No API key, no account, no scraping.

> is the next train to Malpensa on time?

Departures — MILANO CADORNA (S01066), 21:29
  21:23  REG787    SEVESO                       +2'  platform 9
  21:26  REG387    MALPENSA AEROPORTO TERMINA   -2'  platform 1
  21:32  REG887    SARONNO                       0'  platform 6

Install

dotnet tool install -g LombardiaTrains.Mcp

Then register it with your MCP client. For Claude Desktop, in claude_desktop_config.json:

{
  "mcpServers": {
    "lombardia-trains": {
      "command": "lombardia-trains-mcp"
    }
  }
}

For Claude Code:

claude mcp add lombardia-trains -- lombardia-trains-mcp

Tools

Station arguments take either a code (S01700) or a name (milano centrale), and times take either HH:mm for today or ISO 2026-08-29T09:00 for another day.

Three behaviours exist because the caller is a language model rather than a person, and each of them prevents a confident wrong answer:

• now exists at all because a model has no reliable idea of the date in Rome, and every relative question — "tonight", "Saturday" — needs one before any other tool can be called.
• Ambiguous names are never resolved silently. "Milano" matches twenty-six stations, and many towns have both a national station and a separate "Nord" one served by entirely different trains. The tools return the list and ask, rather than picking the first and sounding certain.
• Unknown places say where coverage ends. Asking for Lugano returns an explanation of what the service covers, so the model can decline instead of inventing a train to Switzerland.

find_connection finds direct trains only, and says so. It reads live departure boards and each candidate train's stop list rather than a timetable, so it carries delays and platforms but cannot compose a change.

find_journey composes one. It plans from the regional timetable, falls back to Swiss open data for anywhere that timetable does not reach, and returns scheduled times with no delays in them — the two tools answer different halves of the same question and are meant to be used together.

Journeys are ranked by arrival, not departure. Someone asking how to get somewhere wants to be there soonest, and ranking by departure puts a train that leaves four minutes earlier and arrives forty minutes later at the top of the list.

Only one change is searched for. Two multiply both the search space and the ways to be quietly wrong, and on this network almost everything worth reaching is reachable with one — so the limit is stated rather than hidden behind an incomplete search.

The part worth reading

Both upstream APIs are public, undocumented and a little hostile. Most of the work in this repository is not calling them, it is surviving them. Each of the following is enforced in code and covered by a test.

Trenord wants two headers, not one

Trenord answers 403 Forbidden unless the request carries both an Accept header and a User-Agent:

This is easy to get half right. Probing the endpoint with curl or Python suggests that Accept alone is enough, because both send a User-Agent of their own without being asked. .NET's HttpClient sends neither header unless told to — so a client that sets only Accept keeps getting 403, and finds out in production rather than on the machine where the call was first tried by hand.

That is the whole reason TrenordClient sets both in its constructor.

Optional fields are absent, not null

average_crowding, average_crowding_label, suppression_type and alerts do not appear in the Trenord payload at all when there is nothing to report. They are not null: the properties are missing.

Verified against five regular services (S5, S11, RE_5, R27): none of them carried any of the four. Code that assumes these fields exist therefore works on the trains that have problems and crashes on the ones that do not, which is the worst possible way round.

Timestamps come in three different shapes

• Trenord dep_time / arr_time — local time, "HH:MM:SS". Safe to display.
• Trenord dep_date_time / arr_date_time — ISO 8601 in UTC, with the Z. Convenient for date arithmetic, wrong if you show it as it is.
• ViaggiaTreno — epoch milliseconds, always to be converted declaring Europe/Rome explicitly. Converting with the machine's local time gives the right answer on an Italian laptop and the wrong one on a UTC server.

ViaggiaTreno wants JavaScript's idea of a date

Board endpoints take the timestamp spelled the way Date.toString() spells it:

Mon Aug 10 2026 20:20:00 GMT+0200

Day and month names must be English. They are built from fixed arrays on purpose: formatting them through the machine's culture produces lun ago on an Italian system and the endpoint silently returns nothing.

Two more small ones

• ViaggiaTreno's train lookup answers with plain text, not JSON — one line per run, with the fields needed by the live-progress endpoint after a |.
• It also returns an empty body instead of an empty array when there is nothing to report, which makes a naive deserializer throw.
• train_operator uses $:$ as its separator, literally.

Read the operator's file, not the portal's copy of it

Trenord publishes this timetable as a GTFS zip under CC0, and the same portal also serves it exploded into one queryable table per file. The tables look like the easier option — paged JSON, filterable, no zip to unpack — and they are a lossy copy. Measured against the file they are built from:

A quarter of the timetable does not survive the import, and it does not go missing tidily: trips arrive truncated. Train 11827 runs Varese to Milano and on; in the tables it stops at Porta Garibaldi, so everything reachable by staying on it is invisible, and Varese to Bergamo came back an hour worse than the published answer. Reading the zip, it matches to the minute.

Three more things the import breaks, each of which costs real code to work around and none of which is wrong in the file:

• Times land inside a placeholder date. GTFS writes a service past midnight as 24:05; a datetime cannot hold that, so it becomes 00:05 and the train arrives eighteen hours before it left. The file says 24:05.
• Service ids are rewritten with a hash and no longer match the ones in calendar_dates, so the two files cannot be joined on the key they share. Cutting both back to the number before the hyphen makes them join again — and merges every seasonal variant of a train into one, leaving nothing to say which of them runs today. In the file, trips and calendar_dates both write 1001A-2025-12-14-2026-12-12. The join is exact and the ambiguity does not exist.
• trip_short_name is dropped entirely. That is the train number — the one field that connects a planned leg to the live data.

The decimal point also goes missing from coordinates, and route_type differs: the tables call R23 and RE4 trains, the file calls them buses.

Ask the operator, then say so

The file is not the operator's own answer either, and it is worth being precise about the size of the gap. Checked against 28 journeys published by the operator's own planner, on the same day:

• Milano Centrale to Bergamo: the feed times train 2217 at 48 minutes, the operator at 52.
• Pavia to Mortara: train 10668 arrives 09:28 in the feed, 09:23 in the answer.
• Lecco to Bergamo: train 10719 reaches Ponte S.Pietro at 08:52 in the feed and its connecting coach leaves at 08:51 — a change the feed itself makes impossible and the operator has working with five minutes to spare.

The operator runs HAFAS over an internal timetable with real-time folded in. A GTFS export of it is not it. But the live sources here are the operator's own, and the file carries the train number, so every leg can simply be looked up and asked. Where it answers, its times are the ones shown, the timetable's are kept in brackets beside them, and platforms, delays and cancellations come with them.

Against those same 28 journeys that takes exact agreement from 22 to 27.

The one that remains is the shape of what this cannot do. Lecco to Bergamo is still answered with the 09:01 coach rather than the 08:51 one, because the feed said the train arrived at 08:52 and the search discarded that connection before anything was checked. Correcting after the planning fixes what is shown; it does not recover what the wrong data excluded. Live data is asked for today and tomorrow only — beyond that there is nothing live to ask.

The planner behind the border does not know it is lost

Where the regional timetable does not reach, journeys fall back to Swiss open data. That planner covers Switzerland and reaches into Italy near the border. It does not cover the rest of the country — and asked about it, it does not say so. It matches the name against its own index and answers about whatever it found.

Asked to plan Milano Centrale to Roma Termini, it returned a confident, correctly formatted, two-hour itinerary to LaCLINIQUE of Switzerland, Locarno, Via Bossi 2. Roma Termini to Napoli Centrale became a four-change, four-hour journey ending at a street address in Lucens, canton Vaud.

Nationality is not the test that catches this: the Swiss index holds Zurich, and ViaggiaTreno holds Zurich Altstetten, so "are both stations Italian" rejects a real journey to Zurich while letting the clinic through. The test that works is whether the answer is about the places that were asked for — one substantial word in common, accents folded, so Zurich matches Zürich HB and Roma Termini matches nothing in Locarno. An answer that fails it is discarded rather than passed on, and the reply names the live tools, which do work for those stations.

How accurate this is, and how that was measured

Twenty-eight journeys published by the operator's own planner were compared against what this returns — same day, same times, thirteen routes across the region — and where the two disagreed, the live train data was asked to settle it. Twenty-seven of the twenty-eight match to the minute.

That is a measurement of two things at once, and they are worth separating. The routing was never really the hard part on a network this size: what the number mostly measures is how faithfully open timetable data reproduces the timetable the operator actually runs. The answer is: closely, and not exactly.

An open feed is an export. The operator plans on an internal system with real-time folded into it and publishes a snapshot of that system as GTFS, on its own schedule. A snapshot trails the thing it is a snapshot of — that is what a snapshot is, not a defect of anyone's — and the trailing shows up as a few minutes on a few trains. Four into Bergamo. Five into Mortara. Six into Ponte S.Pietro, where it is the difference between a coach that can be caught and one that cannot.

None of that can be repaired from open timetable data, because the correct value is not in it. What can be done is to stop treating the timetable as the last word: every leg carries a train number, the live sources belong to the operator, so each leg is looked up and asked. That is where twenty-two of twenty-eight became twenty-seven.

The twenty-eighth is the honest edge of the approach. Lecco to Bergamo is still answered with the 09:01 coach rather than the 08:51 one. The feed puts the inbound train into Ponte S.Pietro at 08:52, one minute after that coach leaves, so the search discarded the connection before anything was checked against the operator. Correcting after planning fixes what is shown; it cannot recover what wrong data excluded. Doing better would mean planning on corrected times, which means correcting the whole timetable rather than the handful of legs an answer happens to use — a different project, and a much larger one.

So the position this takes is: be exact about what is known, name the source of every number, and where a minute matters, go and ask the operator. A tool that knows which of its answers to distrust is more useful than one that is confident everywhere.

Coverage

Trenord covers its own fleet, FNM included. ViaggiaTreno covers the RFI network and, unpredictably, part of FNM. So get_train asks Trenord first and falls back to ViaggiaTreno, while the station boards only exist on ViaggiaTreno.

The regional timetable reaches along the cross-border lines, so stations beyond the frontier are planned domestically rather than as an international journey. The live APIs stop at the border, and a leg past it therefore carries scheduled times only.

Development

dotnet build
dotnet test

Fifty tests, on three levels:

• the clients, against the live endpoints — the header rule, the timestamp formats, the empty body where an empty array was expected;
• the tools, called the way a model calls them, asserting on what the answer claims rather than on how it is worded: an ambiguous name comes back as a question, an unknown place says where coverage ends, a planned journey says its times carry no delays;
• the server, started as a process and spoken to in JSON-RPC — the handshake, the advertised tools and their schemas, and the rule that nothing but protocol may reach stdout.

Nothing asserts a departure time. The timetable is republished daily, and a test written around today's 08:24 fails next month for no reason, which teaches whoever reads it to ignore the suite. What is asserted are the properties that hold whatever the timetable says: time moves forward, a change is long enough to make, the journey starts and ends where it was asked to, results are ordered the way the tool claims. Those are also the ones that were actually broken.

They run against the live endpoints on purpose. Mocking would only prove the mocks match what was assumed, and every bug worth catching here came from the real payload disagreeing with the assumption — including the two-header rule above, found by a test contradicting the documentation it was written from.

Requires the .NET 10 SDK.

Limits

• Journey planning covers Lombardy and the cross-border lines. Live data covers all of Italy. Departure boards, arrivals, direct connections and train tracking work at Roma Termini, Napoli Centrale, Palermo and Bari; planning a route between them does not, and says so rather than improvising.
• One change. Two multiply both the search space and the ways to be quietly wrong. Where a journey needs more, the answer says which limit was hit rather than reporting nothing found.
• Times are the operator's where it was asked, and timetabled where it was not. The live sources are asked for today and tomorrow; for any other day there is nothing live to ask, and the answer says so.
• A few minutes on a few trains. The published timetable trails the operator's own by four to six minutes on some services. Legs where the two disagree are marked, and are the legs not to build a four-minute change on.
• Walking between stations is not modelled. Several towns have two stations a few hundred metres apart, served by different lines; a journey that would change between them on foot is not found.
• Read-only. No booking, no ticketing, no account access.
• ViaggiaTreno is served over plain HTTP and is occasionally unavailable.
• The live APIs are undocumented and can change without notice. The tests run against them on purpose: if one starts failing, that is the intended alarm.

Licence

MIT.