index.js•4.02 kB
import { McpServer } from "@modelcontextprotocol/sdk/server/mcp.js";
import { z } from "zod";
const STATION_STATUS_URL = "https://gbfs.citibikenyc.com/gbfs/en/station_status.json";
const STATION_INFO_URL = "https://gbfs.citibikenyc.com/gbfs/en/station_information.json";
function toRad(deg) {
return (deg * Math.PI) / 180;
}
function haversineMeters(lat1, lon1, lat2, lon2) {
const R = 6371000; // meters
const dLat = toRad(lat2 - lat1);
const dLon = toRad(lon2 - lon1);
const a = Math.sin(dLat / 2) ** 2 +
Math.cos(toRad(lat1)) * Math.cos(toRad(lat2)) * Math.sin(dLon / 2) ** 2;
const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a));
return R * c;
}
async function fetchJson(url) {
const res = await fetch(url, { headers: { accept: "application/json" } });
if (!res.ok)
throw new Error(`HTTP ${res.status} for ${url}`);
return res.json();
}
async function getNearestStations({ lat, lon, limit = 5 }) {
const [statusJson, infoJson] = await Promise.all([
fetchJson(STATION_STATUS_URL),
fetchJson(STATION_INFO_URL),
]);
const statusList = statusJson?.data?.stations ?? [];
const infoList = infoJson?.data?.stations ?? [];
const infoById = new Map(infoList.map((s) => [String(s.station_id), s]));
const merged = statusList
.map((st) => {
const id = String(st.station_id);
const inf = infoById.get(id);
if (!inf)
return null;
const distance_m = haversineMeters(lat, lon, Number(inf.lat), Number(inf.lon));
const types = st.num_bikes_available_types || {};
const ebikes = typeof st.num_ebikes_available === "number"
? st.num_ebikes_available
: typeof types.ebike === "number"
? types.ebike
: undefined;
const mechanical = typeof types.mechanical === "number"
? types.mechanical
: typeof st.num_bikes_available === "number" && typeof ebikes === "number"
? Math.max(0, st.num_bikes_available - ebikes)
: undefined;
return {
station_id: id,
name: inf.name,
lat: Number(inf.lat),
lon: Number(inf.lon),
distance_m: Math.round(distance_m),
capacity_total_docks: inf.capacity ?? null,
available_total_bikes: st.num_bikes_available ?? null,
available_ebikes: ebikes ?? null,
available_classic_bikes: mechanical ?? null,
available_docks: st.num_docks_available ?? null,
is_renting: st.is_renting ?? 1,
is_returning: st.is_returning ?? 1,
last_reported: st.last_reported ?? null,
};
})
.filter(Boolean);
merged.sort((a, b) => a.distance_m - b.distance_m);
return merged.slice(0, Math.max(1, Math.min(50, Number(limit) || 5)));
}
export default function createServer({ config }) {
const server = new McpServer({ name: "CitiBike Nearest", version: "0.1.0" });
server.registerTool("nearest_citibikes", {
title: "Nearest Citi Bikes",
description: "Return nearest Citi Bike stations for a lat/lon with distance and ebike/classic availability.",
inputSchema: {
lat: z.number().describe("Latitude in decimal degrees"),
lon: z.number().describe("Longitude in decimal degrees"),
limit: z
.number()
.int()
.min(1)
.max(50)
.optional()
.describe("Max stations to return (1-50). Default 5"),
},
}, async ({ lat, lon, limit }) => {
const results = await getNearestStations({ lat, lon, limit });
return {
content: [
{
type: "text",
text: JSON.stringify({ query: { lat, lon, limit: limit ?? 5 }, stations: results }, null, 2),
},
],
};
});
return server.server;
}