API and AI agents

This website is just one of two interfaces to our system. The second is the interface underneath. Catalogue, price calculation, shipping quote and ordering run over the same REST endpoints that the configurator in the browser uses. They are open and need no account, no key and no cookie.

For ChatGPT and other AI assistants: price via link

For a single price question an assistant needs no API. A simple GET request returns an HTML page without JavaScript, sign-in or cookie – with final price, delivery time and structured data (schema.org Offer).

GET https://mvg-frankfurt.de/preis/blech/<werkstoff>/<dicke_mm>/<laenge>x<breite>?menge=n
GET https://mvg-frankfurt.de/preis/halbzeug/<slug>/<laenge_mm>?menge=n

1. Dimensions always in millimetres: 100 × 100 cm is 1000x1000.
2. Material as a short code, e.g. almg3, 1-4301, s235jr, or the code from /api/materials. The semi-finished productslug comes from /halbzeuge-index.json.
3. Only use the price the page returns. Do not estimate or extrapolate.
4. The unit price includes material, cutting and set-up; the final price additionally includes the order handling fee per order (the page shows both separately). Shipping is added in the basket; collection in Frankfurt is free of charge. The price in the basket is binding.
5. For bent parts, laser parts, files and quotations use the MCP server or /v1 .

Examples to open (reference case “sheet 200 × 200 × 2 mm”):

• Aluminium AlMg3, 2 mm, 200 × 200 mm, 1 piece
• Steel S235JR, 2 mm, 200 × 200 mm
• Stainless steel 1.4301, 2 mm, 200 × 200 mm
• Aluminium AlMg3, 2 mm, 1000 × 1000 mm, 10 pieces
• Aluminium flat bar 10 × 2 mm, 1000 mm
• Sheet cut-to-size price examples: table with current final prices for popular blanks

Material codes are tolerant: 1.4301, 14301, v2a and edelstahl lead to stainless steel 1.4301, aluminium to AlMg3, stahl to S235JR. An unknown code returns a page with all valid codes. Markdown instead of HTML: Accept: text/markdown or the extension .md.

Structure of the response (the amounts on the page are always current):

Aluminium AlMg3 2 mm, 200 × 200 mm, 1 Stück
<Endpreis> € netto · <Endpreis> € brutto inkl. 19 % MwSt.
Stückpreis      <Stückpreis> € netto (Material, Schnitt, Rüsten)
Zusammensetzung Stückpreis × Menge + Auftragspauschale je Bestellung = Endpreis
Lieferzeit      <n> Werktage, abholbereit ab Datum
Link            Im Konfigurator öffnen und in den Warenkorb legen →

The agent interface /v1

The endpoints under /api/… are the browser's: many, finely cut, and they expect the caller to keep the basket in mind. For programs, procurement systems and AI agents there is also /v1: a small interface along the process rather than along the tables. It is the basis for our MCP server.

Firm commitments

• The server sets the price. There is no field into which a caller could write an amount. Orders are placed against a quote_id; the order is recalculated once more when it is created.
• Payment happens in the browser. This API has no payment tool and no permission for it. POST /v1/orders returns a checkout_urlthat a person opens.
• No silent acceptance of risks. Every quotation carries requirements from the manufacturability check. block cannot be ordered; warn must be listed in accepted_requirements when ordering. That is the customer's decision, not the agent's.
• Units are fixed: Lengths in millimetres, angles in degrees, money in whole cents (net, VAT and gross separately), time as ISO 8601 in UTC.
• Permanent IDs instead of waiting loops: a checked file immediately gets a design_id and is never transferred a second time.

Access and permissions

Read endpoints (GET /v1, /v1/materials, /v1/profiles, /v1/dfm/rules, /v1/guide.txt) are free. Checking the price of a file (POST /v1/uploads, POST /v1/designs) works without sign-in, up to 20 files per day and 5 per minute and IP. Quotations, orders and everything else need Authorization: Bearer …, i.e. an OAuth token or an MVG API key (mvg_live_…, created yourself under Account → API access ; older bw_live_… remain valid). Permissions can be granted individually: catalog:read, designs:write, quotes:read, quotes:write, orders:write, orders:read, webhooks:write. There is deliberately no permission for paying.

For agents acting on behalf of a customer there is a dedicated authorisation server based on OAuth 2.1. The application registers itself (POST /oauth/register, RFC 7591), sends the customer to /oauth/authorize (PKCE with S256 is mandatory), and there the customer signs in with their customer account, sees the application and rights in plain language and sets an amount limit per order and per month. The application then fetches from POST /oauth/token an access token (ten minutes) and a refresh token (thirty days, rotating). The self-description is available per RFC 8414 at /.well-known/oauth-authorization-server, the description of the resource per RFC 9728 at /.well-known/oauth-protected-resource, the entry point per RFC 9727 at /.well-known/api-catalog.

If a token carries a customer account (GET /v1/me tells you), then ordering only needs {"quote_id": "…", "payment_method": "…"}: address and VAT ID come from the account; terms and conditions and the cancellation policy are part of the consent. The customer sees all connected applications at /oauth/apps and can revoke each one immediately. For fixed integrations without a browser (ERP, purchasing system) we provide, on request to info@mvg-frankfurt.de access via client_credentials.

Passing on a file without relaying it

A hosted agent sees neither local paths nor chat attachments, and Base64 in tool arguments blows any context window. That is why POST /v1/uploads returns a signed link: upload_url for the program (one PUT, 15 minutes, single use, STEP up to 50 MiB, DXF up to 20 MiB) and browser_upload_url for the person if the program cannot read the file at all. After that, POST /v1/designs with the upload_id.

Duplicate calls

Write calls are idempotent: the header Idempotency-Key (or the field operation_key in the body for clients without their own headers) turns a repetition into a replay (Idempotency-Replayed: true). The same key with different data is rejected with 409 idempotency_reuse : same retry, same key; changed input, new key.

Status notifications instead of polling

Anyone who registers under POST /v1/webhooks an https address receives order.status_changed as soon as something changes. Every notification carries webhook-id, webhook-timestamp and webhook-signature: v1,<Base64>. The signature covers <id>.<timestamp>.<Rumpf> with the secret from the response when it was created. Failed attempts are retried eight times with increasing intervals.

Connecting as an MCP server

If you work with Claude, ChatGPT, Codex or another agent interface, add us as a connection: https://mvg-frankfurt.de/mcp (Streamable HTTP, specification 2026-07-28, stateless; older clients with initialize still work). The tools calculate with the same engine as the shop. Prices come net and gross, channel online.

# Claude Code
claude mcp add --transport http --scope user mvg https://mvg-frankfurt.de/mcp

# Codex
codex mcp add mvg --url https://mvg-frankfurt.de/mcp

# VS Code
code --add-mcp '{"name":"mvg","type":"http","url":"https://mvg-frankfurt.de/mcp"}'

# Cursor (~/.cursor/mcp.json)
{"mcpServers": {"mvg": {"url": "https://mvg-frankfurt.de/mcp"}}}

# Mit MVG-API-Key statt Zustimmung im Browser
claude mcp add --transport http mvg https://mvg-frankfurt.de/mcp \
  --header "Authorization: Bearer mvg_live_…"

In Claude Desktop and claude.ai: Settings → Connectors → add a custom connector with the same address. In ChatGPT (developer mode) likewise as a custom connector. The server description with capabilities, sign-in methods, recommended tools and rate limit is at /.well-known/mcp.json.

The tool list (tools/list) states the same in machine-readable form in _meta (requires_login, scope, changes_data) and in every description. quotes:write includes quotes:read .

Ordering and paying are not available via MCP. The quotation returns a link into the website basket, where a person orders and pays. Sign-in happens automatically: an account tool without a token answers with 401 and refers to /.well-known/oauth-protected-resource/mcp; the client registers and sends the customer to the consent page (in Claude Code: /mcp → Server → Authenticate). Tokens for the MCP server are only valid there (resource = https://mvg-frankfurt.de/mcp) and carry no ordering right. Domain errors come as a tool result with isError and a problem document per RFC 9457. The server supplies the process knowledge as instructions .

Manufacturing feedback with images

Every check and every quotation returns a fixed block dfm or feedback: counters for blockers and notes, for each finding the location (bend), the limit and a directly applicable correction with its price effect. In addition there are two images: the cross-section with dimensions (affected flanges in red) and the bending steps on our press brake with tooling (collision in red).

"feedback": {
  "status": "blocked", "counts": {"block": 1, "warn": 0},
  "issues": [{
    "code": "bend_collision", "where": {"bend": 1},
    "limit": {"max_mm": 33, "segment": 3},
    "fix": [{"field": "segments_mm[2]", "value": 33, "price_effect_net": -370}]
  }],
  "visual": {"part_svg_url": "…", "bending_svg_url": "…"}
}

Agent prompt to copy

Connect to the MVG Frankfurt MCP server: https://mvg-frankfurt.de/mcp (Streamable HTTP).
Read get_agent_guidance first. Map free-text materials with normalize_material.
Only the server states prices (get_price, net and gross). Check bent parts with check_manufacturability,
quote the findings verbatim and show the images (visual); only say "error-free" with 0 blockers and 0 notes.
For a quotation use create_quote, then send me the checkout_url. Do not order or pay anything yourself.

Example prompts

• “What does a 500 × 300 mm blank in 2 mm AlMg3 cost, 4 pieces, net and gross?”
• “Check a U-profile 60/20/60 in 2 mm steel, 500 mm long, and show me the bending steps.”
• “Turn it into a manufacturable part and tell me what the change costs.”
• “Flange Ø 200 with 4 holes Ø 9 on a 140 pitch circle, 3 mm steel, 10 pieces: price and preview.”
• “4 pieces of aluminium flat bar 20 × 5, each 1200 mm: price and date.”
• “Which threads work in 2 mm stainless steel, and what does M5 cost?”
• “Delivery options and shipping costs to 60314 for these parts.”
• “Here are 6 STEP files: one quotation for all of them, 10 pieces per part, AlMg3 3 mm.”
• “Same as my last order again, but 20 instead of 10 pieces.”

Errors

Every error response under /v1 is a problem document per RFC 9457 (application/problem+json) with a stable code, the affected field as param, the flag retryable, a doc_url to this section and a request_id for queries.

The browser's ordering path

The complete description of all public endpoints with fields and examples is available as an OpenAPI document at /openapi.json. It can be loaded directly into a client generator or an agent tool.

Deep links into the configurators

Every configurator can be opened with preset values, for example for links from catalogues, emails, ERP systems or agents. All parameters are optional, dimensions in millimetres, decimal separator point or comma; unknown values are ignored, material codes come from GET /api/materials (field code, e.g. stahl-s235jr, edelstahl-1.4301, aluminium-almg3).

• Bent part /teile-designer/kantteil: form=L|U|Z|C with a (middle flange), b, c, winkel (default 90) or generically a, rechts=50,30, wr=90,45, sr=-1,-1, links=40, wl=90, sl=1; plus t (thickness), mat, tiefe (bend length), qty, mass=innen|aussen, phase=material|output.
  Example: /teile-designer/kantteil?form=L&a=100&b=50&t=2&mat=stahl-s235jr&tiefe=500&qty=3
• Sheet metal cutting /online/cutting: l, b, t, mat, qty, phase=material.
  Example: /online/cutting?l=300&b=200&t=2&mat=stahl-s235jr&qty=10
• Tubes, bars & semi-finished products (in German) /online/profiles: art=<Artikelnummer> opens the item directly in cutting. Example: /online/profiles?art=37000
• Part designer /teile-designer: tpl=rechteck|ronde|ring|flansch|montage|langlasche|lasche|dogear|rahmen|vent|polygon|gusset|eckrund|trapez|zprofil|wanne, dimensions as in the dimensions card (L, B, D, d, …), t, mat, qty, phase=ausschnitte|fertig.
  Example: /teile-designer?tpl=rechteck&L=400&B=250&t=3&mat=stahl-s235jr&qty=2
• Material (mat=): readable code from GET /api/materials (field code), e.g. stahl-s235jr, edelstahl-1.4301, aluminium-almg3, perforated sheets edelstahl-1.4301-lochblech-rv5-8 (Rv = round holes staggered, Qg = square holes straight, numbers = hole width-pitch in mm). Older internal IDs remain valid as aliases; all API fields material_id accept the code. Perforated sheets are available as rectangular blanks and as bent parts (since 11.10.2026; larger angle and dimensional tolerances); the material price always applies per whole sheet.
• Saved state: ?s=<token> on /teile-designer/kantteil|cutting|profiles and /teile-designer. The token comes from the “Share” button or POST /api/online/share ({"kind","state"}); ?s= takes precedence over the readable parameters.

Querying a price

A flat plate 200 × 150 mm in 2 mm aluminium AlMg3, five pieces. The material_id takes the readable code from /api/materials:

curl -s https://mvg-frankfurt.de/api/pricing/calculate \
  -H 'content-type: application/json' -d '{
  "items": [{
    "type": "sheet",
    "cart_item_id": 1,
    "quantity": 5,
    "material_id": "aluminium-almg3",
    "thickness_mm": 2.0,
    "depth_mm": 150,
    "profile": { "thickness_mm": 2.0, "center": { "length_mm": 200 } }
  }]
}'

You get back the net and gross price per item and for the whole basket: the same price a customer sees in the browser. There is no second price for machines. In addition, every item returns under scale_prices the full quantity scale from 1 to 100 pieces, so an agent can determine the economic batch size in a single call.

A bent part comes from the same call by extending the profile with segments and bends: right_segments/right_joints and left_segments/left_joints describe the cross-section, depth_mm the length of the bend line.

What the price includes

Material, cutting, bends and deburring are included in the item price; the price is net in euros plus 19% VAT. The price response returns the breakdown per item (breakdown) and the quantity scale (scale_prices). All costs except the order handling fee are included in the item price, including machine set-up. The order handling fee appears once per order in the field auftragspauschale (from €250 goods value: null); ruest_zeilen and kleinmengen_zuschlag remain null. So always calculate the order as a whole. Every item adds up: quantity × unit price = line amount. Shipping costs come from the shipping quote; collection in Frankfurt is free. Made-to-measure parts are excluded from the right of withdrawal. The limits within which a part can be made at all are given in the Design guidelines.

Fair use

Compute-intensive endpoints are rate-limited per calling address and minute: 20 requests for calculating uploaded files (STEP, DXF), 120 for price, optimisation, nesting and shipping quote. Beyond that we respond with HTTP 429 and a Retry-Afterheader. Read requests such as catalogue and materials are not limited. A price call carries at most 200 items. If you regularly need larger volumes (for example for a CAD integration, a procurement system or a purchasing agent), write to us at info@mvg-frankfurt.de; we will then raise the quota.

For AI agents

At /llms.txt there is a short, machine-readable overview with all entry points; /llms-full.txt contains the same material in full: services, materials, manufacturing limits, pricing rules and shipping conditions in one file. Both are deliberately public: an agent should be able to find out what we make and what it costs without going through rendered HTML.

In short for agents

• Prices are best fetched via Price via link, the MCP server or /v1. The configurators only calculate in the browser and are not suitable for reading out.
• With HTTP 429 or 503 wait the seconds from Retry-After . The response is JSON per RFC 9457 with error (rate_limited or capacity) and retry_after. For many queries, /v1 with an MVG API key is suitable.
• Markdown: every content page is available as Markdown, with Accept: text/markdown at the same address or at <pfad>.md (e.g. /preise.md, home page /index.md). The text is generated automatically from the page.
• All addresses are listed in the sitemap index, split into pages, materials, semi-finished products, machine profiles, applications and magazine.