Immoprobe for your assistant

Immoprobe (https://immoprobe.de) is a calculator and a system of record for German residential investment properties (Kapitalanlage-Immobilien): cashflow before and after tax, yields, AfA, a 30-year projection, the land value (Bodenrichtwert) the valuation board publishes for the address, saved objects with notes. It runs no language model. You read the listing; Immoprobe does the maths.

If you have the Immoprobe tools (MCP connector)

Call get_guide once, then lookup_address, calculate_property and save_object. How to connect: https://immoprobe.de/ai.

If you have no tools: hand the user a link

Read the listing — its URL, or the text or PDF the user pasted. If you cannot open the URL, say so and ask for the text; do not answer with a template of placeholders. If the page opens but does not show the unit the URL names (a project page with many units), say so and ask for its text — never take another unit of the project in its place.
Build a link to the calculator with what the listing states: https://immoprobe.de/calculator?purchasePrice=…&livingArea=…&stateCode=…&coldRent=… with the parameters below. Fill every field the listing states — the Baujahr or, for a new build, the Fertigstellung as handover and yearBuilt, the Hausgeld, the Provision as hasBroker, the address as address — and always listingUrl, title, your note, model and assumed. Leave out only what the listing does not say. URL-encode the values; numbers with a decimal point and without thousands separators; money in EUR; rates in percent. When the listing names no rent, estimate a realistic Kaltmiete for the place and put coldRent into assumed.
If your web tool can open a URL you composed yourself, open the same query at https://api.immoprobe.de/v1/calculations?… (the link with https://immoprobe.de/calculator replaced): it answers the calculation as text — cashflow, yields, tax effect, the verdict, the assumptions it used — and you quote it. Never compute cashflow or yields yourself. The chat apps of ChatGPT, Claude and Gemini open only URLs the user gave or that a page they read contained, never one you composed — there, and when your tool opens no pages at all, skip this step and leave the numbers to the page; say so in one line.
With the property's point — lat and lng from the page, or the ones you determined for a full address, an assumption then — open https://api.immoprobe.de/geo/brw/at?lng=<lng>&lat=<lat>: zones[0].brw is the land value (Bodenrichtwert) the valuation board published, in EUR per m² of plot as of stichtag, gfz the GFZ of the zone; put them into the link as landValuePerSqm and floorAreaRatio and name the Stichtag and the source (src) to the user. Empty zones means no data there — say so, never guess a land value. The same path answers flood (hazard zones), designations (Milieuschutz, Sanierungsgebiet, Denkmal), noise, transit (stations within 3 km), location (Mietspiegel Wohnlage) and census.
Answer with the link as plain text in a code block — not as a hyperlink, so the user can copy it as it is — and, in the user's language, what you read, what you guessed, and what to ask the agent. Write the link in one piece and finish it before anything else; check that every value in it is URL-encoded. After sign-in the page also looks up the land value at the point.

The user opens the link, sees the calculation and saves the property with one click; your note becomes its first note, your assumed fields are marked as assumptions.

The listing

Parameter	Meaning
`listingUrl`	the listing's page; Immoprobe reads the portal and the listing id from it
`title`	a title for the saved object, up to 120 characters
`address`	the address as the listing writes it, a label only
`lat`, `lng`	the point of the property when the page shows it (ImmoScout24 does on the exposé map); with it the land value follows
`note`	your assessment: what the numbers do not show — Erbbaurecht, Instandhaltungsrücklage, Sanierungsstau, Denkmalschutz, Energieausweis, the rent against the Mietspiegel, WEG-Protokolle, Sonderumlagen — and a block „Fragen an den Makler“; markdown, in the user's language, short — a few lines, under 600 characters; a longer explanation goes into your answer, not into the link
`model`	your name (ChatGPT, Gemini, Claude …), shown with the note
`assumed`	the calculator fields you guessed rather than read, comma-separated

The calculator's fields

Required: purchasePrice, livingArea, stateCode, coldRent. Every other field is optional and takes a default when left out; the page lists the defaults it used as assumptions.

Field	Meaning
`purchasePrice`	Kaufpreis, EUR
`livingArea`	Wohnfläche, m²
`yearBuilt`	Baujahr; decides the AfA rate
`stateCode`	Bundesland, two-letter code (BE, NW, BY …); sets the Grunderwerbsteuer
`notaryPercent`	Notar, % of the purchase price
`landRegistryPercent`	Grundbuch, % of the purchase price
`brokerPercent`	Käuferprovision, % of the purchase price; counts only with hasBroker
`hasBroker`	Whether a Provision is due; "provisionsfrei" is false
`movablesInPrice`	Inventar (Einbauküche, furniture) inside the purchase price, EUR; outside the Grunderwerbsteuer base
`movablesExtra`	Inventar bought on top of the purchase price (Ablöse), EUR
`movablesUsefulLife`	Useful life of the Inventar, years: 10 for a kitchen, 13 for furniture
`renovationCost`	Renovierung right after the purchase, EUR incl. VAT; the 15 % rule decides AfA or deduction in year one
`coldRent`	Kaltmiete per month, EUR
`parkingRent`	Stellplatz or garage rent, EUR per month, apart from coldRent
`serviceCharge`	Hausgeld, the whole monthly charge, EUR
`serviceChargeRecoverable`	Umlagefähiger Teil of the Hausgeld the tenant reimburses, per month, EUR
`otherCosts`	Running costs outside the Hausgeld (Sondereigentumsverwaltung, insurance, upkeep), EUR per month
`serviceChargeReserve`	Erhaltungsrücklage part of the Hausgeld, EUR per month; not deducted from tax until the WEG spends it
`equity`	Eigenkapital, EUR; when given, ltv is ignored
`ltv`	Beleihungsauslauf: loan on the object in % of the purchase price, as a bank quotes it; side costs come from equity. Used when equity is left out
`interestRate`	Sollzins, % per year
`repaymentRate`	Anfängliche Tilgung, % of the loan per year
`fixedRateYears`	Sollzinsbindung of the bank loan, years (1–40); afterwards the loan continues at interestRate plus followUpRateDelta
`followUpRateDelta`	Rate change after the Sollzinsbindung, percentage points; 0 continues the Sollzins. A scenario, never a listing figure
`specialRepayment`	Sondertilgung on the bank loan, EUR per year, during the Sollzinsbindung; a plan, never a listing figure
`kfwAmount`	KfW-Darlehen, EUR: a tranche of the loan, never on top of it; 0 or left out means none. Send only what the user names
`kfwInterestRate`	Sollzins of the KfW tranche, % per year, for its ten-year Zinsbindung
`kfwTermYears`	Laufzeit of the KfW tranche, years (4–35)
`kfwGraceYears`	Tilgungsfreie Anlaufjahre of the KfW tranche: 1–2 on a term to 10 years, up to 3 to 25, up to 5 to 35
`kfwRepaymentMode`	annuity (default) or bullet, an endfälliges Darlehen of up to 10 years
`handover`	Übergabe/Fertigstellung month of a new build bought before completion, YYYY-MM (a quarter as its last month); the months from the contract to it are the Bauphase. Left out, the property is ready
`contractMonth`	Month of the Kaufvertrag, YYYY-MM, once it is signed; left out, this month. Anchors the Bauphase and the building age
`commitmentFreeMonths`	Bereitstellungszinsfreie Zeit of the bank loan, months (0–36); counts only with a Bauphase
`commitmentFeeRate`	Bereitstellungszins of the bank loan, % per month on the undrawn part once the bereitstellungszinsfreie Zeit is over (0–1; 3 % p. a. is 0.25); counts only with a Bauphase
`landShare`	Bodenwertanteil, % of the price that is land (not depreciable). Send it when the Kaufvertrag or Bauträger states the split; left out, derived from landValuePerSqm and the plot share, else 20 assumed
`landValuePerSqm`	Bodenrichtwert, EUR per m² of plot, as lookup_address answers it
`plotArea`	Grundstücksfläche: the whole plot, m²
`coOwnershipShare`	Miteigentumsanteil numerator: 56 of "56/10.000"; 1 for a house bought whole
`coOwnershipTotal`	Miteigentumsanteil denominator: 10000 of "56/10.000"; 1 for a house bought whole
`floorAreaRatio`	GFZ of the Bodenrichtwert zone from lookup_address; estimates the plot share when plotArea and Miteigentumsanteil are unknown
`taxRate`	Grenzsteuersatz incl. Soli, %
`depreciationVariant`	AfA route: linear2, linear25, linear3, declining5, declining7b, monument, remainingLife; left out, the Baujahr decides
`renovationShare`	Sanierungsanteil under § 7i, % of the building value; monument route only
`remainingUsefulLife`	Restnutzungsdauer from an appraisal, years; remainingLife route only
`rentGrowth`	Mietsteigerung, % per year
`costGrowth`	Kostensteigerung, % per year
`valueGrowth`	Wertsteigerung, % per year
`vacancyMonths`	Mietausfallwagnis, vacancy months per year

Where a German listing says it

„Kaufpreis“ → purchasePrice; „Wohnfläche“ → livingArea; „Baujahr“ → yearBuilt.
„Kaltmiete“, „Nettokaltmiete“, „Mieteinnahmen (kalt)“ → coldRent per month; a yearly figure divided by 12.
„Stellplatz“, „Tiefgarage“ let for a monthly rent → parkingRent, apart from coldRent; split a rent quoted „inkl. Stellplatz“ when the listing names the part.
„Hausgeld“ → serviceCharge per month; the umlagefähiger Teil, when stated, → serviceChargeRecoverable; „davon Instandhaltungsrücklage“ or „Erhaltungsrücklage“ → serviceChargeReserve per month (paid, but not deducted from tax until the WEG spends it).
„Provision“, „Käuferprovision“ → hasBroker=true and brokerPercent; „provisionsfrei“ → hasBroker=false.
A renovation the user plans right after the purchase → renovationCost in EUR incl. VAT; „renovierungsbedürftig“ in the listing is a reason to ask for the amount, never to guess one.
The state from the postcode or the city → stateCode: BE Berlin, BB Brandenburg, BW Baden-Württemberg, BY Bayern, HB Bremen, HE Hessen, HH Hamburg, MV Mecklenburg-Vorpommern, NI Niedersachsen, NW Nordrhein-Westfalen, RP Rheinland-Pfalz, SH Schleswig-Holstein, SL Saarland, SN Sachsen, ST Sachsen-Anhalt, TH Thüringen.
„Grundstück 1.500 m²“ → plotArea=1500; „Miteigentumsanteil 56/10.000“ → coOwnershipShare=56&coOwnershipTotal=10000.
A new build bought before completion: „Fertigstellung Q3 2027“ → handover=2027-09 (a quarter as its last month, „Winter 2026“ as 2026-12) and yearBuilt = the year of the Fertigstellung — without it the calculator assumes an old building and the wrong AfA rate; „degressive AfA“ in the listing → depreciationVariant=declining5; „Sonder-AfA“, „§ 7b“ or „QNG“ (Effizienzhaus 40 mit Qualitätssiegel Nachhaltiges Gebäude) → depreciationVariant=declining7b, the degressive route plus the special allowance of the first four years.
Financing is the user's, never the listing's: equity in EUR or ltv in percent of the price, only when the user named them. A portal's „Finanzierungsbeispiel“ (Eigenkapital, Tilgung, Monatsrate) is advertising, not the user's plan — leave it out. KfW only when the user names an amount.

Example

https://immoprobe.de/calculator?purchasePrice=395000&livingArea=74&stateCode=BE&coldRent=1250&yearBuilt=1910&serviceCharge=310&hasBroker=true&lat=52.548&lng=13.36&address=Malplaquetstra%C3%9Fe%2027%2C%2013347%20Berlin&listingUrl=https%3A%2F%2Fwww.immobilienscout24.de%2Fexpose%2F123456789&title=Altbau%20Wedding&note=Erbbaurecht%20nicht%20erw%C3%A4hnt%20%E2%80%93%20nachfragen.&model=ChatGPT&assumed=serviceCharge

Conduct

Read only listings the user opened or asked you to open, at a human pace. Never bypass a captcha or a login wall — stop and ask. Do not contact sellers or agents. Do not put the agent's contact details into the note unless the user asks.