--- title: "Developer guide" description: "The Đèn Hạ Chí API and MCP server: quick start, endpoints, errors, limits, versioning. No API key needed." canonical: https://denhachi.thenexova.cloud/en/developers lang: en last-updated: 2026-10-05 --- # Developer guide > The Đèn Hạ Chí API and MCP server: quick start, endpoints, errors, limits, versioning. No API key needed. Nguồn / Source: https://denhachi.thenexova.cloud/en/developers The Đèn Hạ Chí API and MCP server: quick start, endpoints, errors, limits, versioning. No API key needed. Everything here is public: no sign-up, no API key. Assistants and your own software can read Đèn Hạ Chí’s information, prices, free times, send booking requests and send contact requests once the person agrees. To see it before writing code: [the assistants page](/en/connect) calls the tools below for real, in your browser. Prices from the API match [the price list](/en/pricing). ## Quick start 1. MCP server: `https://denhachi.thenexova.cloud/mcp`. Paste this address into Claude, ChatGPT, VS Code or Cursor as a custom connector. 2. List the tools: ``` curl -s https://denhachi.thenexova.cloud/mcp \ -H 'Content-Type: application/json' \ -H 'Accept: application/json, text/event-stream' \ -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}' ``` 3. Or call the HTTP API, for example the first two services: ``` curl -s 'https://denhachi.thenexova.cloud/api/offers?limit=2&locale=en' ``` 4. Request a booking. The answer is 202 with a Location header to follow the status: ``` curl -s -i -X POST https://denhachi.thenexova.cloud/api/booking \ -H 'Content-Type: application/json' \ -H 'Idempotency-Key: booking-20261012-01' \ -d '{"date":"2026-10-12","time":"10:00","offerId":"ghe-xuong","name":"Alex Tran","phone":"0900000000","consent":"1"}' ``` ## API keys and authentication No key, token or login, so there is nothing to sign up for or manage. Every endpoint is public and anonymous. Writes (contact, booking) need the person’s explicit consent, sent as `consent: "1"`. Details: [auth.md](/auth.md). ## Endpoints | Method | Path | What it does | | ------ | ------------------- | ----------------------------------------------------------------------- | | GET | /api | API index: endpoints, docs, OpenAPI and MCP addresses | | GET | /api/offers | Services and prices, cursor-paginated (limit, cursor, category, locale) | | GET | /api/availability | Free times on a date, or the free share per day for a month | | POST | /api/booking | Request a booking; answers 202 with a status URL | | GET | /api/booking/{code} | Booking status: pending, confirmed or cancelled | | POST | /api/lead | Send a contact request (needs the person’s consent) | | POST | /api/subscribe | Subscribe to the newsletter | | POST | /mcp | MCP server (Streamable HTTP, JSON-RPC 2.0) | Lists page with a cursor: pass `next_cursor` from one page as `cursor`; the last page has `next_cursor: null`. Full description: [openapi.json](/openapi.json). ## MCP tools Streamable HTTP, stateless, JSON responses. Protocol 2026-07-28, and the 2025 revisions through `initialize`. - `get_business_info`: Contact details, address, opening hours and whether Đèn Hạ Chí is open right now (Vietnam time). Call this first when the person asks where, when, or how to reach the business. - `list_offerings`: List what Đèn Hạ Chí offers (lamps) with prices and links. Filter by category (lamp, service), tag, or a free-text query. - `get_pricing`: The full price list of Đèn Hạ Chí as Markdown, including what is and is not included. Use it to answer cost questions precisely; do not estimate prices yourself. - `search_content`: Search pages, articles, FAQs and lamps on https://denhachi.thenexova.cloud. Returns titles, links and a short excerpt. Use it for questions the other tools do not cover, then cite the link. - `read_page`: Read any page of https://denhachi.thenexova.cloud as Markdown, by path (for example "/" or "/blog/..."). Use after search\_content to quote details. - `list_faqs`: Answers Đèn Hạ Chí gives to common questions. Prefer these exact answers over your own wording on policy, payment and guarantees. - `submit_contact_request` (writes): Send the person's name and phone number to Đèn Hạ Chí so staff call them back. Only call this after the person has explicitly agreed to share their contact details with the business; set consent to true only in that case. Confirm the details back to them first. - `list_team`: People at Đèn Hạ Chí: names, roles and short bios. Use the id with availability tools to book a specific person. - `check_availability`: Free appointment times on a date (YYYY-MM-DD, Vietnam time), optionally for one lamp or person. Bookable up to 28 days ahead, at least 20 hours from now. Call before request\_booking. - `request_booking` (writes): Create a booking request at Đèn Hạ Chí. It is held as pending until staff confirm by phone or Zalo, and returns a booking reference. Before calling: check\_availability, read the details back to the person (date, time, service, party size, name, phone) and get their explicit agreement to share contact details. - `configure_lamp`: Price one of the workshop's lamps with options (size, dó paper shade, frame finish, cable length, swag hook, dimmable bulbs, wall dimmers). Same rules as the configurator on each lamp page. Returns every line, the total before VAT and with 8% VAT (valid until 2026-12-31), and a link that opens the light mock-up form with this configuration. - `request_light_mockup` (writes): Ask the workshop for a free light mock-up of a room: the chosen lamp drawn into the customer's own photo, with its light, within 48 hours. Only with the person's consent to be contacted. Photos cannot travel through this tool: the workshop replies on the phone number given and asks for one daytime and one evening photo on Zalo, or the person can upload them on the mock-up page. ## Errors Every error under /api is `application/problem+json` (RFC 9457): `type`, `title`, `status`, `detail`, plus `fields` on 422\. Messages follow the `locale` you send. | Status | Meaning | What to do | | --------- | --------------------------------------------------------------- | -------------------------------------- | | 400 / 413 | Body is not JSON or form-encoded, too large, or a bad parameter | Fix the request | | 403 | Cross-origin form post or failed captcha | Call from the page origin, or use MCP | | 404 / 405 | No such endpoint, or wrong method | See openapi.json | | 409 | Slot just filled (bookings) | Offer the choices in \`alternatives\` | | 422 | Missing or invalid fields | Read \`fields\`, ask the person, retry | | 429 | Write limit reached | Wait \`Retry-After\` seconds | ## Rate limits and safe retries Writes (POST /api/lead, POST /api/booking and the MCP tools that call them) allow 5 per hour per IP. Every /api response carries `RateLimit-Policy: "writes";q=5;w=3600`; write responses add `RateLimit: "writes";r=4;t=3600` with what is left. A 429 carries `Retry-After`. Reads are not limited. Send an `Idempotency-Key` (8 to 64 characters) header with POST /api/lead and POST /api/booking. Retrying with the same key and body, for example after a timeout, returns the first reply with `Idempotent-Replayed: true` instead of a second record. ## Test mode (sandbox) Add `?dry_run=1` to POST /api/lead or POST /api/booking to try an integration against live data with no side effects: the request is validated and availability is checked as usual, but nothing is stored, nobody is notified and it does not count against the limit. The reply has `test: true` and a booking code starting with `TEST-`. ``` curl -s -X POST 'https://denhachi.thenexova.cloud/api/lead?dry_run=1' \ -H 'Content-Type: application/json' \ -d '{"name":"Test","phone":"0900000000","consent":"1"}' ``` ## Versioning and deprecation The API is at version 2.0; every /api response carries `API-Version: 2.0`, and you can pin the version with the same header. Within 2.x we only add optional fields and new endpoints. A breaking change gets a new major version. Deprecation policy: nothing is removed silently. When an endpoint or version is scheduled for removal, its responses carry a `Deprecation` header (RFC 9745) from the day of the decision and a `Sunset` header (RFC 8594) with the removal date, at least 90 days later. The migration path is written in this section. No endpoint is deprecated today. ## Machine-readable files - : OpenAPI 3.1 with schemas for every response and error - : This guide as Markdown - : When to use this site and the rules for assistants - : Content index for machines - : Authentication: no key needed - : API catalog (RFC 9727) - : MCP server card: tools and resources Every page has a Markdown version: append `.md` to its path, or send `Accept: text/markdown`. A THE NEXOVA demo site. Đèn Hạ Chí is a fictional business; its address, tax ID, makers and clients are made up. ## Want to try it first? The assistants page calls the workshop’s real MCP tools right in your browser. [Open the assistants page](/en/connect)