gtfs-one-mcp

A Model Context Protocol server that turns any GTFS One transit site into a set of tools for AI assistants. Point it at an agency's WordPress site and Claude, ChatGPT, or any other MCP-compatible client can answer rider questions from the agency's live GTFS and GTFS-Realtime data — nearest stops, next departures, routes, live bus positions, and service alerts.

It talks to the site's public REST API (/wp-json/gtfs-one/v1/*) — no plugins, no database access, no credentials required. One MCP server covers one transit site (which may host multiple agency feeds).

Why this exists: the only other transit MCP servers are single-agency, hard-coded hobby projects. This one works with any GTFS One install, driven entirely by configuration.

Tools

The realtime tools (get_service_alerts, get_live_vehicles) never error on missing data — an empty result means "nothing active right now," not "no service." The tool descriptions tell the AI this explicitly.

Related MCP server: marta-mcp

Requirements

• Node.js 18 or newer

• A transit website running GTFS One 1.5+ with its REST API publicly reachable

Configuration

Provide settings via a JSON config file or environment variables (env vars win where both are set). Only the site URL is required.

// gtfs-one.config.json
{
  "gtfs_one_url": "https://your-agency-site.org",
  "feed_id": "default",
  "cache_ttl_seconds": 30,
  "agency_name": "Your Transit Agency",
  "agency_description": "Public transit serving ... (cities, landmarks, region)."
}

Pass a non-default config path with --config /path/to/config.json or the GTFS_ONE_CONFIG env var.

Use with Claude Desktop

Edit claude_desktop_config.json (Settings → Developer → Edit Config) and add:

{
  "mcpServers": {
    "gtfs-one-transit": {
      "command": "npx",
      "args": ["-y", "gtfs-one-mcp"],
      "env": {
        "GTFS_ONE_URL": "https://your-agency-site.org",
        "GTFS_ONE_FEED_ID": "default",
        "GTFS_ONE_AGENCY_NAME": "Your Transit Agency"
      }
    }
  }
}

Restart Claude Desktop, then ask: "What bus stops are near <a place in the service area>?" or "When's the next bus from <stop name>?"

Windows users: Claude Desktop on Windows can't launch npx directly (it's a .cmd shim, not an executable), so the server silently fails to start and Claude falls back to web search. Wrap the command in cmd instead:

{
  "mcpServers": {
    "gtfs-one-transit": {
      "command": "cmd",
      "args": ["/c", "npx", "-y", "gtfs-one-mcp"],
      "env": {
        "GTFS_ONE_URL": "https://your-agency-site.org",
        "GTFS_ONE_FEED_ID": "default",
        "GTFS_ONE_AGENCY_NAME": "Your Transit Agency"
      }
    }
  }
}

After editing, fully quit Claude Desktop (right-click the system-tray icon → Quit — closing the window isn't enough) and reopen it.

Use with ChatGPT / other MCP clients

Any client that launches a local stdio MCP server works the same way — run npx -y gtfs-one-mcp with the same environment variables, or install globally:

npm install -g gtfs-one-mcp
GTFS_ONE_URL=https://your-agency-site.org gtfs-one-mcp

Remote / hosted connector (Streamable HTTP)

The stdio setup above only works in clients that launch a local process (classic Claude Desktop, Cursor, etc.). The Claude apps that use remote connectors — the newer desktop app and claude.ai on the web — instead add an MCP server by URL. For those, run the server in HTTP mode and host it somewhere with a public HTTPS address; then add that URL as a custom connector.

Run it in HTTP mode:

GTFS_ONE_URL=https://your-agency-site.org \
GTFS_ONE_AGENCY_NAME="Your Transit Agency" \
PORT=3000 \
gtfs-one-mcp-http        # or: npm run start:http

This serves the MCP endpoint at /mcp (and a /healthz check). Extra env:

Deploy

• Docker: a Dockerfile is included — docker build -t gtfs-one-mcp . && docker run -p 3000:3000 -e GTFS_ONE_URL=… -e GTFS_ONE_AGENCY_NAME=… gtfs-one-mcp

• Render / Railway / Fly.io (Node): build npm install && npm run build, start npm run start:http, set the env vars. A render.yaml blueprint is included; Render gives you HTTPS automatically.

• Your own VPS: run behind nginx/Caddy with TLS, proxying to the Node port.

The data is public and read-only, so an open endpoint is fine; add MCP_AUTH_TOKEN if you'd rather gate it.

Add it to Claude

In the Claude desktop app or claude.ai: Settings → Connectors → Add custom connector, give it a name, and paste your server's URL ending in /mcp (e.g. https://gtfs-one-mcp.onrender.com/mcp). Then ask a transit question and you'll see the gtfs-one-transit tools used.

Local development

npm install
npm run build       # compile TypeScript to dist/
node test/smoke.mjs # exercise all 9 tools against a live site

How it fits together

Local (stdio):
AI client  ──MCP/stdio──►  gtfs-one-mcp  ──HTTPS──►  GTFS One REST API
(Desktop)                  (local process)           /wp-json/gtfs-one/v1/*

Remote (Streamable HTTP):
AI client  ──MCP/HTTPS──►  gtfs-one-mcp-http  ──HTTPS──►  GTFS One REST API
(web/app)                  (hosted service /mcp)          /wp-json/gtfs-one/v1/*

Both transports share the same nine tools and config — pick stdio for local clients (Claude Desktop, Cursor) or HTTP for connector-based clients (the Claude app, claude.ai web, ChatGPT).

License

GPL-2.0-or-later © Digital Mountaineers