--- name: bodenrichtwert-mcp description: Use this skill whenever someone asks for the Bodenrichtwert (official German land value, EUR/m²) of an address, or wants a Bodenwert/Bodenrichtwert recalculated for a different Geschossflächenzahl (GFZ). The rule is absolute — always call the real bodenrichtwert.ai MCP server for the number, never answer from memory, training data, or a web search. user-invocable: true --- **Never answer a Bodenrichtwert or Bodenwert question from memory, training data, or a web search.** These are official appraisal values published by German Gutachterausschüsse and change over time (they carry a `Stichtag`/reference date) — a remembered or searched-up number is not verifiable and must not be presented as authoritative. Always get the number from the real, live bodenrichtwert.ai MCP server via `get_bodenrichtwert` / `calculate_bodenwert` (see below). If the server isn't reachable or isn't connected, say so plainly and offer to help connect it — do not fall back to an estimate. If invoked without further guidance: ask for a complete German address (street, house number, postal code, city) if one wasn't given, then call `get_bodenrichtwert`. ## Calling the server This works the same way regardless of which LLM or client you're running in — bodenrichtwert.ai is a standard MCP server, not a Claude-only integration. **If the bodenrichtwert.ai connector/plugin is already connected** in your client (Claude Desktop, claude.ai Connectors, a ChatGPT Connector/App, or any other MCP-capable client): its tools are available under the names `get_bodenrichtwert` and `calculate_bodenwert` — possibly with a client-specific prefix or namespace in front of the name. Look for those tool names in your connected-tools list and call them directly. No further setup needed. **If it isn't connected yet:** add `https://mcp.bodenrichtwert.ai/mcp` as an MCP connector/plugin in your client. The client handles OAuth discovery and login automatically — you (or the end user) get sent to a browser login, no manual token needed. Full protocol details (RFC 9728 discovery, PKCE flow, token exchange) are in [`docs/authentifizierung.md`](../../../docs/authentifizierung.md) and root [`CLAUDE.md`](../../../CLAUDE.md) (§ MCP OAuth Flow) — this skill won't repeat them. ## Tool reference For quick orientation only — if this ever disagrees with your client's live `tools/list` response, trust the live response, not this copy. **`get_bodenrichtwert`** - `address` (string, required) — full German address incl. postal code, e.g. `"Unter den Linden 1, 10117 Berlin"`. - `nutzungsart` (optional, string or array of strings) — filter to one or more use-type codes: `W` Wohnbau, `M` Mischgebiet, `G` Gewerbe, `S` Sonderbau, `L` Landwirtschaft, `F` Forst, `SO` Sonstige. Omitted → all use types present at the address are returned structured; the text summary highlights only the most relevant one, in priority order `W > M > G > S > L > F > SO`. - Returns (per zone): `nutzungsart`, `code`, `brw_euro_pro_m2`, `stichtag`, `gemeinde`, `gutachterausschuss`, plus optional planning figures (`bodenrichtwertnummer`, `zonenbezeichnung`, `bauweise`, `geschossflaechenzahl`, `grundflaechenzahl`, `vollgeschosszahl`, `baumassenzahl`, `wertrel_geschossflaechenzahl`) when the Gutachterausschuss publishes them — not every one does. **`calculate_bodenwert`** — pure computation, no data lookup. - `brw` (number, required) — the input Bodenrichtwert in EUR/m². - `gfz_referenz` (number, required) — the GFZ the input value refers to (from `wertrel_geschossflaechenzahl` on a prior `get_bodenrichtwert` call, if published). - `gfz_tatsaechlich` (number, required) — the actual/permitted GFZ of the plot. - `flaeche` (number, optional) — plot area in m²; if given, also returns the total `bodenwert_euro`. - Formula: `K(GFZ) = 0.6·√GFZ + 0.2·GFZ + 0.2`, `BRW_tatsächlich = BRW × K(GFZ_ist) / K(GFZ_ref)`. Orientational — does not replace a Gutachterausschuss's zone-specific official conversion table. ## Answer rules / compliance - **Always carry the attribution forward** when relaying a value: `dl-de/by-2-0` license, visible to whoever reads your answer. - **Always state what the number is, and isn't**: a gutachterlicher Orientierungswert (official appraisal reference value) for unbuilt land — not a Verkehrswert, not a purchase/asking price, and not legal or tax advice. For a real transaction, recommend a qualified Sachverständiger/Gutachter. - **Schleswig-Holstein, Sachsen, Bayern have no data.** The server will tell you this — explain it to the person asking, don't try to work around it (no alternative-source guessing). - **Multiple use types at one address**: without an explicit `nutzungsart` filter you get all zones back structured; when summarizing in prose, lead with the highest-priority one (`W > M > G > S > L > F > SO`), but don't discard the others if the user cares about a specific Nutzungsart. - **Values shift over time** — always mention the `stichtag` (reference date) of the value you're quoting. ## Error cases The MCP server reports tool-level errors inside the tool result itself (`isError: true` in the response), not as an HTTP error — this is normal, not a sign anything is broken. | Situation | What to tell the person | |---|---| | Address not found | The address couldn't be geocoded/matched — ask them to double-check spelling, house number, or postal code. | | Restricted state (SH/SN/BY) | No Bodenrichtwerte are published for that Bundesland via this service — say so, don't substitute a guess. | | No data at that location | No zone exists at those coordinates for the requested Nutzungsart(en) — try without a `nutzungsart` filter, or confirm the address is on buildable land. | | Service error | The official upstream source is temporarily unreachable — suggest retrying shortly. | | Limit reached | The connected account's quota is exhausted — point to upgrading rather than guessing a value in the meantime. | ## Example Real output from the live server (not fabricated), for `"Unter den Linden 1, 10117 Berlin"`: ```json { "address_resolved": "Unter den Linden 1, 10117 Berlin - Mitte", "bodenrichtwerte": [{ "nutzungsart": "Gemischte Baufläche", "code": "M", "brw_euro_pro_m2": 9500, "stichtag": "2026-01-01", "gemeinde": "Berlin", "gutachterausschuss": "Gutachterausschuss für Grundstückswerte in Berlin", "bodenrichtwertnummer": "00001132", "wertrel_geschossflaechenzahl": 4.5 }], "attribution": { "text": "© Daten der Gutachterausschüsse für Grundstückswerte 2026, dl-de/by-2-0", "license_url": "https://www.govdata.de/dl-de/by-2-0", "year": 2026 }, "disclaimer": "Amtlicher Bodenrichtwert gemäß dl-de/by-2-0. Gutachterlicher Orientierungswert — kein Verkehrswert, kein Verkaufspreis, keine Rechtsberatung. Stichtag pro Eintrag beachten." } ``` And `calculate_bodenwert` for `brw: 1640, gfz_referenz: 1.0, gfz_tatsaechlich: 1.5, flaeche: 500`: ```json { "faktor": 1.2348, "bodenrichtwert_tatsaechlich_euro_pro_m2": 2025.15, "grundstuecksflaeche_m2": 500, "bodenwert_euro": 1012574.48 } ``` A restricted-state call (`"Marienplatz 8, 80331 München"`) comes back with `isError: true` and the text "Bayern stellt aktuell keine Bodenrichtwerte bereit." — exactly the case described above, not a malfunction.